# CVE-2026-118178: Mozilla Thunderbird RSS feed URL redirection to file: URL

Source: https://junglewise.ai/threats/cve-2026-118178-a-remote-rss-feed-could-use-the-itunes-new-feed-url-or  
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-2026-118178 · Severity: info · Published 2026-10-27

Thunderbird, an email and RSS feed client, fails to validate RSS feed subscription URL changes, allowing a malicious or intercepted feed to redirect users to local files or network shares. An attacker can exploit this to read local files on any platform or steal Windows NTLM credentials through network share access. This could expose sensitive files or compromise user authentication credentials.

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

## Quick answers

**Is CVE-2026-118178 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118178 being exploited in the wild.

**How severe is CVE-2026-118178?** 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-2026-118178?** 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-2026-118178 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-118178?** 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

The vulnerability exists in Thunderbird's handling of RSS feed redirection elements (itunes:new-feed-url or newLocation), which can be exploited to permanently change a stored subscription URL to a file: URL. Thunderbird then attempts to read from this location on every feed update without validating the URL scheme. An attacker with a malicious RSS feed or one able to modify feeds over HTTP can trigger local file reads (all platforms) or NTLM credential leaks on Windows when accessing remote network shares.

## 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=2075772](https://bugzilla.mozilla.org/show_bug.cgi?id=2075772)
- [https://www.mozilla.org/security/advisories/mfsa2026-121/](https://www.mozilla.org/security/advisories/mfsa2026-121/)

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- [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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