What’s Vulnerable › Vulnerabilities

CVE-2021-29982

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-08-17 · updated 2026-06-17
• Weakness: CWE-772

Description

Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting in the potential leak of a single bit of memory. This vulnerability affects Firefox < 91 and Thunderbird < 91.

Affected products

• Mozilla Firefox: before 91.0 — fixed in 91.0
• Mozilla Thunderbird: before 91.0 — fixed in 91.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 91.0; Mozilla Thunderbird 91.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1715318
• 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=1715318
• https://security.gentoo.org/glsa/202202-03
• https://www.mozilla.org/security/advisories/mfsa2021-33/
• https://www.mozilla.org/security/advisories/mfsa2021-36/

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