This vulnerability allows an XML External Entity (XXE) vulnerability within AssertJ, specifically affecting versions 1.4.0 through 3.27.6. The issue arises in the `org.assertj.core.util.xml.XmlStringPrettyFormatter` class, particularly in the `toXmlDocument(String)` method, which does not disable DTDs or external entities when initializing the `DocumentBuilderFactory`. This oversight can lead to serious security risks when processing untrusted XML input.
The CVSS score for this vulnerability is 8.2, categorizing it as high severity. Organizations should take this threat seriously, as it allows attackers to exploit untrusted XML inputs to read arbitrary local files or perform Server-Side Request Forgery (SSRF) attacks. Additionally, it opens the possibility for Denial of Service via "Billion Laughs" entity expansion attacks.
Given the nature of this vulnerability, it is imperative for organizations utilizing AssertJ to act swiftly. The recommended steps include upgrading to version 3.27.7, replacing the deprecated `isXmlEqualTo(CharSequence)` method with XMLUnit, or ensuring that untrusted XML inputs are not processed using the vulnerable methods.
Organizations should prioritize patching immediately.
Vulnerability Details
The vulnerability is identified as CVE-2026-24400, with a CVSS score of 8.2, indicating high severity. The affected product is AssertJ, specifically in versions from 1.4.0 to 3.27.6. This vulnerability is classified under CWE-611, which pertains to XML External Entity (XXE) vulnerabilities.
Technical Analysis
The root cause of this vulnerability is the initialization of the `DocumentBuilderFactory` with default settings. This allows DTDs and external entities to be processed without restrictions, leading to potential exploit scenarios. The attack vector is local, requiring low attack complexity, and only low privileges are necessary to exploit this vulnerability. Importantly, no user interaction is required, making it easier for attackers to leverage this vulnerability.
The impacts of this vulnerability are significant. If exploited, attackers could gain access to sensitive files through local file reads, perform SSRF attacks, or cause a denial of service. Confidentiality could be severely impacted, while integrity remains unaffected.
Risk & Impact Analysis
Organizations utilizing AssertJ should assess the risk associated with this vulnerability in their deployment environments. The potential for an attacker to read sensitive files or perform SSRF attacks poses a considerable threat, especially if untrusted XML inputs are processed. The urgency is high, given the severity of the vulnerability and the potential impacts on confidentiality and availability.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability impacts AssertJ versions from 1.4.0 to 3.27.6. Organizations should ensure they are on version 3.27.7 or later to mitigate this risk.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to AssertJ version 3.27.7 or later. Additionally, replacing the `isXmlEqualTo(CharSequence)` method with XMLUnit is highly recommended. If immediate upgrades can't be performed, avoid using these methods with untrusted XML input.
For further guidance on securing XML input processing, organizations are encouraged to refer to the OWASP XML External Entity Prevention Cheat Sheet.
Penetration testing can help identify vulnerabilities in your applications before they are exploited.
Detection Guidance
Organizations should monitor logs for any indicators of exploitation, such as unexpected file read attempts or unusual HTTP requests that could indicate SSRF. Behavioral anomalies in application performance may also signal attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-24400 highlights the ongoing issue of XML External Entity vulnerabilities in modern applications. As applications increasingly handle untrusted data, the potential for exploitation through XXE remains a relevant threat.
Security teams should take note of this vulnerability as a reminder to implement stringent input validation and to regularly review and update dependencies to mitigate risks.
For additional resources, consider reviewing our penetration testing methodology to strengthen your security posture.
Furthermore, understanding the patterns of vulnerability exploitation can help teams prepare for potential threats. Engage in proactive measures to build resilience against similar vulnerabilities in the future.
Staying informed about emerging vulnerabilities and threats is crucial for maintaining security in today's environment. Leverage our resources to enhance your security practices.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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