Signatures are written to disk before and read during verification, which might be subject to a race condition when a malicious local process or user is replacing the file. This vulnerability affects Thunderbird < 78.10.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-29948
• https://bugzilla.mozilla.org/show_bug.cgi?id=1692899
• https://www.mozilla.org/security/advisories/mfsa2021-14/