What’s Vulnerable › Vulnerabilities

CVE-2021-29957

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-06-24 · updated 2026-06-17

Description

If a MIME encoded email contains an OpenPGP inline signed or encrypted message part, but also contains an additional unprotected part, Thunderbird did not indicate that only parts of the message are protected. This vulnerability affects Thunderbird < 78.10.2.

Affected products

• Mozilla Thunderbird: before 78.10.2 — fixed in 78.10.2

How to fix

Upgrade to a fixed version: Mozilla Thunderbird 78.10.2. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1673241
• https://www.mozilla.org/security/advisories/mfsa2021-22/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1673241
• https://www.mozilla.org/security/advisories/mfsa2021-22/

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