Thunderbird's update mechanism allowed a medium-integrity user process to interfere with the SYSTEM-level updater by manipulating the file-locking behavior. By injecting code into the user-privileged process, an attacker could bypass intended access controls, allowing SYSTEM-level file operations on paths controlled by a non-privileged user and enabling privilege escalation. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.
A race condition existed in nsHttpTransaction that could have been exploited to cause memory corruption, potentially leading to an exploitable condition. This vulnerability was fixed in Firefox 137.0.2.
JavaScript code running while transforming a document with the XSLTProcessor could lead to a use-after-free. This vulnerability was fixed in Firefox 137, Firefox ESR 115.22, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.
A crafted URL containing specific Unicode characters could have hidden the true origin of the page, resulting in a potential spoofing attack. This vulnerability was fixed in Firefox 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.
Memory safety bugs present in Firefox 136, Thunderbird 136, Firefox ESR 128.8, and Thunderbird 128.8. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.
An attacker could read 32 bits of values spilled onto the stack in a JIT compiled function. This vulnerability was fixed in Firefox 137 and Thunderbird 137.
Leaking of file descriptors from the fork server to web content processes could allow for privilege escalation attacks. This vulnerability was fixed in Firefox 137 and Thunderbird 137.
After selecting a malicious Windows `.url` shortcut from the local filesystem, an unexpected file could be uploaded.
*This bug only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 137 and Thunderbird 137.
Memory safety bugs present in Firefox 136 and Thunderbird 136. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 137 and Thunderbird 137.
Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape.
The original vulnerability was being exploited in the wild.
*This only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1.