CVE-2026-126134: Feed subscriptions could leak NTLM credentials on Windows

Published Nov 10, 2026
·
Updated

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.

Affected Software

2 affected componentsFixes available
Mozilla Thunderbird<160
160
Mozilla Thunderbird<153.7
153.7

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 160
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 153.7
  3. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 160
  4. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 153.7

Event History

Nov 10, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
CVE Published
via MITRE·06:59 PM
Data Sourced
via MITRE·06:59 PM
Description
Data Sourced
via NVD·07:21 PM
Description

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Who is affected by this issue?

Only Thunderbird users on Windows are affected. Other operating systems are unaffected.

2

What must an attacker do to exploit it?

The attacker must trick a user into subscribing to a feed whose file: URL points to a network share controlled by the attacker. When Thunderbird fetches that feed, it connects to the attacker's server and Windows sends the user's NTLM credentials.

3

Which Thunderbird version contains the fix?

The issue was fixed in Thunderbird 160.

Company

Resources

Contact

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