CVE-2021-43539

moderate-risk

Published 2021-12-08

Failure to correctly record the location of live pointers across wasm instance calls resulted in a GC occurring within the call not tracing those live pointers. This could have led to a use-after-free causing a potentially exploitable crash. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

Do I need to act?

0.97% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 8.8/10 High

NETWORK / LOW complexity

Affected Products (6)

Firefox

Firefox Esr

Thunderbird

Debian Linux

Affected Vendors

Debian Mozilla

References (20)

Issue Tracking https://bugzilla.mozilla.org/show_bug.cgi?id=1739683

Mailing List https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html

Mailing List https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html

Third Party Advisory https://security.gentoo.org/glsa/202202-03

Third Party Advisory https://security.gentoo.org/glsa/202208-14

Third Party Advisory https://www.debian.org/security/2021/dsa-5026

Third Party Advisory https://www.debian.org/security/2022/dsa-5034

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2021-52/

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2021-53/

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2021-54/