Bug 2561893

Summary:	CVE-2026-113868 thunderbird: Thunderbird: information disclosure via malformed authentication challenge [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Vipul Nair <vinair>
Component:	thunderbird	Assignee:	Jan Horak <jhorak>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide	CC:	jhorak, klaas, rstrode, suraj.ghimire7
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["b0c65eb3-12c6-4227-9235-419b3b7fccef"]}
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2556405

Description Vipul Nair 2026-10-27 11:51:46 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.