CVE-2026-126134

Feed subscriptions could leak NTLM credentials on Windows

Published Nov 10, 2026 CVSS 3.1 · 6.1 Medium EPSS < 1% KEV · Not listed
Description
Thunderbird allowed feed subscriptions to file: URLs that point to a network share. If a user was tricked into subscribing to such a URL, Thunderbird connected to the attacker's server when fetching the feed. Windows then sent the user's NTLM credentials to that server.
This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4898-1 thunderbird security update
History
Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
Weaknesses CWE-201
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
Description Thunderbird allowed feed subscriptions to file: URLs that point to a network share. If a user was tricked into subscribing to such a URL, Thunderbird connected to the attacker's server when fetching the feed. Windows then sent the user's NTLM credentials to that server. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 160. Thunderbird allowed feed subscriptions to file: URLs that point to a network share. If a user was tricked into subscribing to such a URL, Thunderbird connected to the attacker's server when fetching the feed. Windows then sent the user's NTLM credentials to that server. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7.
References
Type Values Removed Values Added
Description Thunderbird allowed feed subscriptions to file: URLs that point to a network share. If a user was tricked into subscribing to such a URL, Thunderbird connected to the attacker's server when fetching the feed. Windows then sent the user's NTLM credentials to that server. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 160.
Title Feed subscriptions could leak NTLM credentials on Windows
References

Subscriptions

No data.

Weaknesses

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Nov 10, 2026, 8:24 PM
Reserved
Nov 10, 2026, 6:59 PM
Status
Awaiting Analysis
Published
Nov 10, 2026, 7:21 PM
Modified
Nov 10, 2026, 9:19 PM
Severity
Moderate
Public date
Nov 10, 2026, 6:59 PM