# CVE-2026-118176: thunderbird: Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypass...

CVE-2026-118176 is fixed in thunderbird on 1 platform, first by DEBIAN-CVE-2026-118176, released October 31, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-118176
- Priority: High
- CVSS: 8.1 (high)
- EPSS: 0.0040
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 27, 2026

## Description

Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name and NTLM authentication data, which could be used for offline password cracking or relay attacks. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | thunderbird Debian 12.15 (bookworm) | 1:153.6.0esr-1~deb12u2 | [DEBIAN-CVE-2026-118176](https://patchblox.com/security/data/fix/linux/debian-cve-2026-118176.md) | Oct 31, 2026 |
| Linux | thunderbird Debian 13.5 (trixie) | 1:153.6.0esr-1~deb13u1 | [DEBIAN-CVE-2026-118176](https://patchblox.com/security/data/fix/linux/debian-cve-2026-118176.md) | Oct 31, 2026 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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