# CVE-2026-118174: Mozilla Thunderbird OpenPGP key attachment remote content loading

Source: https://junglewise.ai/threats/cve-2026-118174-when-a-message-containing-an-openpgp-key-attachment-was  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-118174 · Severity: info · Published 2026-10-27

Thunderbird, an email and calendar client, automatically loaded OpenPGP key attachments from arbitrary URLs when displaying a message, bypassing security protections that normally block such remote content. On Windows systems, attackers could exploit this to steal Windows account credentials; on other systems, the attack bypassed remote content blocking policies.

Technologies: [Mozilla Thunderbird](https://junglewise.ai/threats/technologies/thunderbird). Vendors: [Mozilla](https://junglewise.ai/threats/vendors/mozilla).

## Quick answers

**Is CVE-2026-118174 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118174 being exploited in the wild.

**How severe is CVE-2026-118174?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Mozilla Thunderbird before 159 and before 153.6.

**Is there a fix for CVE-2026-118174?** Yes: fixed in Thunderbird 159, Thunderbird 153.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-118174 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-118174?** Check whether you run Mozilla Thunderbird at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Thunderbird 159, Thunderbird 153.6

## Technical details

When displaying an email with an OpenPGP key attachment marked as an external attachment, Thunderbird automatically fetched the content from the provided URL without user interaction, circumventing remote content blocking. On Windows, an attacker-controlled SMB share URL could leak NTLM credentials; on other OSes, it bypassed content restrictions. The vulnerability affects OpenPGP key import functionality and requires only that a user view a crafted email.

## Affected products

- Mozilla Thunderbird before 159 and before 153.6

## Timeline

- 2026-10-27: disclosed
- 2026-10-27: patched

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2080910](https://bugzilla.mozilla.org/show_bug.cgi?id=2080910)
- [https://www.mozilla.org/security/advisories/mfsa2026-121/](https://www.mozilla.org/security/advisories/mfsa2026-121/)

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- [Mozilla Thunderbird SMTP/POP3 response injection via STARTTLS](https://junglewise.ai/threats/cve-2026-126135-if-an-attacker-was-able-to-perform-a-man-in-the-middle-attack-on)
- [Thunderbird NTLM credential leak via feed subscription to file URL](https://junglewise.ai/threats/cve-2026-126134-thunderbird-allowed-feed-subscriptions-to-file-urls-that-point)
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- [Thunderbird attachment replacement disclosure via link files](https://junglewise.ai/threats/cve-2026-126132-when-a-message-was-forwarded-inline-edited-as-new-or-had-an)