CVE-2024-55875

The vulnerability present in the HTTP toolkit for Kotlin applications involves an XML External Entity Injection (XXE) flaw, which can be exploited when the library processes malicious XML content within incoming requests. This type of vulnerability occurs when an application parses XML input from untrusted sources without proper validation or sanitization. Attackers can craft XML payloads that include references to external entities, allowing them to manipulate the XML parser into accessing local files or making network requests to external systems. The potential for this vulnerability to expose sensitive information stored on the server, or to facilitate server-side request forgery (SSRF), poses significant risks to the integrity and confidentiality of the affected systems.

Exploitation of this vulnerability can occur through various attack vectors. An attacker could send a specially crafted XML request to a vulnerable application that utilizes the affected toolkit, which would then be parsed by the server. If the application does not implement adequate controls, the attacker could gain access to local files, such as configuration files containing sensitive credentials, or trigger requests to internal services that should not be accessible externally. In more severe scenarios, if the application has the capability to execute code based on the XML input, an attacker could potentially execute arbitrary code, leading to a complete compromise of the server. This multifaceted nature of the attack makes it particularly dangerous, as it can lead to a chain of exploits that escalate the attacker's privileges.

The real-world impact of such vulnerabilities can be profound, especially for organizations that handle sensitive data or operate critical infrastructure. The ability to read local files can lead to the exposure of sensitive information, including user data, API keys, and other confidential information. Furthermore, SSRF attacks can enable attackers to pivot within the network, potentially accessing internal services that are not exposed to the internet. The business risks associated with these types of vulnerabilities include financial losses, reputational damage, and regulatory penalties, particularly for organizations subject to data protection regulations. The high CVSS score of 9.8 reflects the severe implications of a successful exploitation, emphasizing the urgent need for organizations to address this vulnerability.

To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-layered security approach. First, it is crucial to upgrade to the patched version of the toolkit, which addresses the XXE vulnerability. Additionally, developers should adopt secure coding practices, such as validating and sanitizing XML input, to ensure that only trusted data is processed. Implementing security controls like Web Application Firewalls (WAFs) can help detect and block malicious requests before they reach the application. Regular security audits and penetration testing should also be conducted to identify potential vulnerabilities and ensure that security measures are effective. Finally, educating developers and security teams about the risks associated with XML processing and the importance of secure coding practices can further reduce the likelihood of exploitation.

In conclusion, the XXE vulnerability in the HTTP toolkit for Kotlin applications represents a significant threat to the security of web applications. The potential for sensitive information exposure, server-side request forgery, and arbitrary code execution necessitates immediate attention from organizations using the affected library. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can take proactive steps to mitigate risks and protect their systems from exploitation.

CSURFACE threat intelligence has detected a marked increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2024-55875, reflecting a nearly 50% rise in the likelihood of exploitation. This upward trend, coupled with a recent emergence of publicly available proof-of-concept exploits on GitHub, signals growing attacker interest and capability to leverage the XXE vulnerability in http4k. Although the increase is not yet classified as rapid, the sustained upward trajectory over the past week indicates that threat actors are actively developing or refining exploitation techniques. For defenders, this escalation underscores an elevated risk environment where the potential for sensitive data exposure, server-side request forgery, and remote code execution is becoming more imminent. Consequently, the threat level associated with this vulnerability has intensified, warranting heightened vigilance in monitoring and detection efforts within environments utilizing the affected http4k versions.

Update 2 — July 25, 2026

CSURFACE threat intelligence has identified a marked escalation in exploitation attempts targeting CVE-2024-55875, accompanied by the emergence of new proof-of-concept exploits circulating within underground forums and public repositories. This development signals that threat actors are transitioning from reconnaissance and initial probing to active exploitation phases, increasing the likelihood of successful compromise. Our telemetry indicates that these activities are not yet widespread but are gaining momentum, suggesting that adversaries are refining their tactics to bypass existing detection mechanisms. The presence of publicly available exploit code lowers the barrier to entry for less sophisticated attackers, thereby broadening the threat actor landscape. Consequently, the risk level associated with this vulnerability has shifted from elevated to critical, as the probability of exploitation in operational environments has substantially increased. Defenders should recognize that the window for proactive defense is narrowing as adversaries intensify efforts to weaponize this flaw.