thunderbird: When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was...
CVE-2026-113868 is fixed in thunderbird on 1 platform, first by DEBIAN-CVE-2026-113868, released October 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.
When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64. A malicious server could send a challenge that caused Thunderbird to include uninitialized heap memory in its NTLM response, disclosing that memory to the server. A challenge consisting only of base64 padding also caused an out-of-bounds read, crashing Thunderbird. This affected accounts configured to use NTLM or GSSAPI authentication. The uninitialized memory disclosure only affected NTLM. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| thunderbird · Debian 12.15 (bookworm) | 1:153.5.1esr-1~deb12u1 | DEBIAN-CVE-2026-113868 | Oct 27, 2026 |
| thunderbird · Debian 13.5 (trixie) | 1:153.5.1esr-1~deb13u1 | DEBIAN-CVE-2026-113868 | Oct 27, 2026 |
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