CVE-2025-4093

Vulnerability

CVE-2025-4093 is a memory safety bug in Firefox ESR 128.9 and Thunderbird 128.9 involving the Wayland buffer release callback handler. The crash analysis [1] indicates a use-after-free condition where the WaylandBuffer object is released before the buffer release callback fires, leaving a dangling pointer that gets dereferenced. This leads to memory corruption, as evidenced by the SIGSEGV crash with a corrupted mBufferReleaseFunc pointer (0xe5e5e5e5e5e5e5e5) [1].

Exploitation

The vulnerability is triggered through the Wayland display protocol, which is used in desktop Linux environments. An attacker could potentially exploit this by crafting malicious Web content or other inputs that interact with Wayland buffers. No special privileges are required from the attacker's perspective, but the bug only affects systems running under Wayland. The crash volume increased significantly, suggesting broader exploitability [1].

Impact

If successfully exploited, the memory corruption could allow an attacker to execute arbitrary code in the context of the affected product. Mozilla considers this vulnerability high severity, and the crash patterns suggest it is reliably exploitable with enough effort.

Mitigation

Mozilla has fixed this vulnerability in Firefox ESR 128.10 and Thunderbird 128.10, as announced in security advisories [2][3]. Users are advised to update to the latest versions to mitigate the risk.