What’s Vulnerable › Vulnerabilities

CVE-2021-29949

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-24 · updated 2026-06-17
• Weakness: CWE-427

Description

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Affected products

• Mozilla Thunderbird: before 78.9.1 — fixed in 78.9.1

How to fix

Upgrade to a fixed version: Mozilla Thunderbird 78.9.1. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1682101
• https://www.mozilla.org/security/advisories/mfsa2021-13/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1682101
• https://www.mozilla.org/security/advisories/mfsa2021-13/

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