Vulnerability Description
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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2076569
- https://www.mozilla.org/security/advisories/mfsa2026-114/
- https://www.mozilla.org/security/advisories/mfsa2026-115/
FAQ
What is CVE-2026-113868?
CVE-2026-113868 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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...
How severe is CVE-2026-113868?
CVE-2026-113868 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-113868?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.