---
id: "CVE-2026-126134"
page: "https://infrastack.ai/live/CVE-2026-126134"
kind: "vulnerability"
aliases: ["CVE-2026-126134"]
title: "Thunderbird on Windows leaks NTLM credentials via feed file share URLs"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "thunderbird", "windows"]
not_affected_if: ["feed-subscriptions-unused", "non-windows"]
published_at: "2026-11-10T19:21:14+00:00"
first_seen_at: "2026-11-10T19:25:15+00:00"
updated_at: "2026-11-10T20:04:48+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126134", "first_seen_at": "2026-11-10T19:25:15+00:00"}]
exploit_sources: []
---

# Thunderbird on Windows leaks NTLM credentials via feed file share URLs

Link for people: https://infrastack.ai/live/CVE-2026-126134 (this .md is for agents)

Thunderbird accepted feed subscriptions pointing to file: URLs on network shares. When a user is tricked into subscribing, Windows sends the user's NTLM credentials to the attacker's server.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Thunderbird version (Help > About Thunderbird) and compare it with the fixed version below.
- Only Windows installs are affected; `unknown` whether other checks apply.

## Fix

- Thunderbird: `160`

## Timeline

- 2026-11-10T19:25:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-126134

## From the sources

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.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_