Overview
The Common Vulnerabilities and Exposures (CVE) system has recently identified a serious flaw in libxslt, a prominent library used for parsing XSLT documents. This vulnerability, indexed as CVE-2025-7425, has the potential to compromise systems and lead to data leakage if left unaddressed. The flaw lies in the attribute type, or atype, flags, where improper modification can corrupt internal memory management. Given the widespread use of libxslt in various applications, this vulnerability could have significant implications for a wide range of users, from individual consumers to large corporations. Addressing this issue is of paramount importance to maintaining the security and integrity of systems worldwide.
Vulnerability Summary
CVE ID: CVE-2025-7425
Severity: High (7.8 CVSS Score)
Attack Vector: Remote
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
libxslt | All versions prior to patch
How the Exploit Works
The vulnerability arises from a flaw within the attribute type flag modification process in libxslt. When certain XSLT functions such as the key() process result in tree fragments, the corruption prevents the proper cleanup of ID attributes. This leads to instances where the system may access freed memory. This memory corruption is detrimental as it can cause unexpected system crashes. Furthermore, a malicious attacker can exploit this flaw to trigger heap corruption, compromising the system or leading to potential data leakage.
Conceptual Example Code
A conceptual example of how this vulnerability might be exploited is as follows:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:key name="vulnkey" match="doc" use="."/>
<xsl:template match="/">
<xsl:variable name="treefrag">
<doc/>
</xsl:variable>
<xsl:apply-templates select="key('vulnkey', $treefrag)"/>
</xsl:template>
</xsl:stylesheet>This XSLT stylesheet creates a tree fragment that activates the flawed key() function, leading to heap corruption as discussed above.
Recommended Mitigation
The best mitigation for CVE-2025-7425 is to apply the patch provided by the vendor as soon as it is available. If the patch is not immediately available or cannot be applied promptly, temporary mitigation can be achieved by using a Web Application Firewall (WAF) or Intrusion Detection System (IDS). These systems can be configured to identify and block attempts to exploit this vulnerability. However, these are interim solutions and the vendor’s patch should be applied as soon as possible to fully address this issue.
