CVE-2021-29981

8.8 highEPSS 1.0%

High (8.8) in mozilla. EPSS 1.0% chance of exploitation in the next 30 days.

An issue present in lowering/register allocation could have led to obscure but deterministic register confusion failures in JITted code that would lead to a potentially exploitable crash. This vulnerability affects Firefox < 91 and Thunderbird < 91.

Severity

CVSS 3.1

8.8 high

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS: 1.0% chance of exploitation in the next 30 days; higher than 63% of CVEs (scores of 2026-10-31)
Published: 2021-08-17
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1707774
https://security.gentoo.org/glsa/202202-03
https://www.mozilla.org/security/advisories/mfsa2021-33/
https://www.mozilla.org/security/advisories/mfsa2021-36/
https://bugzilla.mozilla.org/show_bug.cgi?id=1707774

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