Description

Mozilla has urgently rolled out security updates to fix a severe Firefox vulnerability, CVE-2025-5262, which enables attackers to execute arbitrary code on victims systems without requiring any user interaction. Cybersecurity experts highlight the severity of this flaw, emphasizing that attackers can exploit it effortlessly as users engage in routine web browsing. The security flaw originates from a double-free memory corruption problem within the libvpx library, a crucial component in Firefox's VP8 and VP9 video processing for WebRTC. The issue arises in the vpx_codec_enc_init_multi function due to improper handling of failed memory allocations during the encoder initialization process. Mozilla’s security advisory explains that a double-free could happen in vpx_codec_enc_init_multi after a failed allocation, potentially leading to memory corruption and an exploitable crash. This inconsistency causes confusion at the call site, as other failures in vp8e_init() do not trigger ownership transfer, resulting in both the caller and vpx_codec_destroy() freeing the same memory block, ultimately leading to the double-free condition. Cybersecurity analysts have deemed this a severe security flaw, assigning it a CVSS score of 9.8, highlighting the high risk of exploitation. Because it exists in WebRTC, a widely used protocol for real-time communication, attackers could exploit it by simply directing victims to a malicious webpage. In order to enhance security, Mozilla released an update on May 27, 2025 that resolved the libvpx vulnerability in Firefox 139, Firefox ESR 128.11, and Firefox ESR 115.24. Originally contributed by James Zern from Google, the patch ensures that mr_ related variables* are correctly cleared upon failure, preventing the double-free memory corruption issue.