CVE-2025-5262 in Firefox
Summary
by MITRE • 05/27/2025
A double-free could have occurred in `vpx_codec_enc_init_multi` after a failed allocation when initializing the encoder for WebRTC. This could have caused memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 139, Firefox ESR < 115.24, and Firefox ESR < 128.11.
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Analysis
by VulDB Data Team • 08/20/2025
The vulnerability identified as CVE-2025-5262 represents a critical memory safety issue within the WebRTC encoder implementation of Mozilla Firefox browsers. This double-free condition occurs during the initialization phase of the video encoder through the vpx_codec_enc_init_multi function, specifically when memory allocation fails during the encoding setup process. The flaw manifests when the system attempts to release memory that has already been freed, creating a scenario where subsequent memory operations can corrupt the heap structure and potentially allow arbitrary code execution.
The technical root cause of this vulnerability lies in improper memory management within the VP8 and VP9 video codec initialization routines used by Firefox's WebRTC implementation. When the encoder initialization process encounters a memory allocation failure, the code path fails to properly handle the cleanup sequence, leading to the same memory block being freed twice. This type of vulnerability falls under the common weakness enumeration CWE-415, which specifically addresses double free conditions in memory management operations. The flaw demonstrates a classic example of inadequate error handling in resource cleanup routines where the failure to properly track memory allocation states results in heap corruption.
The operational impact of this vulnerability extends beyond simple crash conditions to potentially enable remote code execution within the context of the browser process. Attackers could exploit this weakness by crafting malicious WebRTC sessions that trigger the specific allocation failure scenario, causing the browser to execute the double-free operation. This creates a memory corruption condition that could be leveraged to execute arbitrary code, particularly when combined with other exploitation techniques such as heap spraying or information disclosure. The vulnerability affects a wide range of Firefox versions including the mainline Firefox 138 and its extended support releases, making it a significant concern for organizations relying on these browser versions for WebRTC functionality.
Organizations should prioritize immediate patching of affected Firefox versions to address this vulnerability, as the potential for remote code execution makes it a high-severity threat. The recommended mitigation strategy involves updating to Firefox 139 or later versions for the main release, Firefox ESR 115.24 or later for the 115.x extended support release, and Firefox ESR 128.11 or later for the 128.x extended support release. Security teams should also implement network monitoring to detect potential exploitation attempts targeting this specific vulnerability. Additional protective measures include enabling Firefox's built-in security features such as sandboxing and content security policies, which can limit the potential impact should exploitation occur. The vulnerability aligns with ATT&CK technique T1203, which covers legitimate program execution through the exploitation of memory corruption vulnerabilities in web browsers.