CVE-2022-26485 in Firefox
Summary
by MITRE • 12/22/2022
Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability identified as CVE-2022-26485 represents a critical use-after-free flaw in Mozilla's Firefox browser and related applications that stems from improper handling of XSLT parameters during processing. This vulnerability specifically targets the XSLT (Extensible Stylesheet Language Transformations) engine within the browser's rendering stack, where memory management issues can occur when parameters are removed or modified during active processing. The flaw allows attackers to manipulate the memory state of the application, potentially leading to arbitrary code execution. The vulnerability has been actively exploited in the wild, with reports indicating that threat actors have developed working exploits that take advantage of this memory corruption issue. The affected software versions include Firefox prior to 97.0.2, Firefox ESR prior to 91.6.1, Firefox for Android prior to 97.3.0, Thunderbird prior to 91.6.2, and Focus prior to 97.3.0, indicating a broad impact across Mozilla's product ecosystem.
The technical nature of this vulnerability aligns with CWE-416, which describes use-after-free conditions where memory is accessed after it has been freed, and is particularly concerning due to its potential for remote code execution. When an XSLT parameter is removed during processing, the application's memory management system may not properly handle the cleanup of associated resources, leaving pointers to freed memory that can be manipulated by attackers. This type of memory corruption vulnerability is particularly dangerous because it can be exploited through web content, allowing attackers to execute arbitrary code with the privileges of the compromised browser process. The attack vector typically involves crafting malicious XSLT content that triggers the problematic code path, where the application's handling of parameter removal creates a race condition or improper memory state that can be exploited through memory corruption techniques.
The operational impact of this vulnerability extends beyond simple browser compromise, as it can lead to complete system compromise when attackers leverage the use-after-free condition to execute malicious code. The fact that this vulnerability has been observed in the wild indicates that attackers have developed reliable exploitation techniques that can be deployed against unsuspecting users. The affected applications represent critical components of Mozilla's security ecosystem, with Firefox serving as a primary web browser and Thunderbird as a widely-used email client, making the potential attack surface substantial. The vulnerability's presence in both desktop and mobile versions of Firefox and related applications demonstrates that threat actors are actively targeting multiple platforms and user bases. Additionally, the inclusion of Focus browser in the affected list shows that even mobile browser applications are vulnerable to this type of memory corruption attack, highlighting the need for comprehensive security updates across all Mozilla products.
Mitigation strategies for CVE-2022-26485 primarily focus on immediate software updates and patches provided by Mozilla to address the underlying memory management issues in the XSLT processing engine. Organizations and users should prioritize updating all affected Mozilla applications to their patched versions, as the vulnerability has been actively exploited in real-world scenarios. Security administrators should also consider implementing network-based protections such as content filtering and web application firewalls to block potentially malicious XSLT content that might exploit this vulnerability. Browser hardening techniques including sandboxing and memory protection mechanisms can provide additional layers of defense, though these are secondary to the primary patching approach. The vulnerability's classification as a use-after-free condition also emphasizes the importance of regular security assessments and code reviews focused on memory management practices, particularly in components that handle dynamic content processing. Given the ATT&CK framework's categorization of such vulnerabilities under privilege escalation and code execution techniques, organizations should also ensure their incident response procedures include detection and remediation of potential exploitation attempts targeting this specific memory corruption flaw.