Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2021-11-03

[ Description ]Official description

Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.

CISA: Mozilla Firefox and Thunderbird contain a race condition vulnerability when handling a ReadableStream under certain conditions. The race condition creates a use-after-free vulnerability, causing unspecified impacts.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 3 May 2022): Apply updates per vendor instructions.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• bugzilla.mozilla.org/show_bug.cgiIssue TrackingPermissions Required
• usn.ubuntu.com/4335-1Third Party Advisory
• www.mozilla.org/security/advisories/mfsa2020-11Vendor Advisory
• www.mozilla.org/security/advisories/mfsa2020-14Vendor Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource