What’s Vulnerable › Vulnerabilities

CVE-2021-38498

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-11-03 · updated 2026-06-17
• Weakness: CWE-416

Description

During process shutdown, a document could have caused a use-after-free of a languages service object, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.

Affected products

• Mozilla Firefox: before 93.0 — fixed in 93.0
• Mozilla Firefox ESR: before 91.2 — fixed in 91.2
• Mozilla Thunderbird: before 91.2 — fixed in 91.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 93.0; Mozilla Firefox ESR 91.2; Mozilla Thunderbird 91.2. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1729642
• https://www.mozilla.org/security/advisories/mfsa2021-43/
• https://www.mozilla.org/security/advisories/mfsa2021-45/
• https://www.mozilla.org/security/advisories/mfsa2021-47/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1729642
• https://www.mozilla.org/security/advisories/mfsa2021-43/
• https://www.mozilla.org/security/advisories/mfsa2021-45/
• https://www.mozilla.org/security/advisories/mfsa2021-47/

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