# CVE-2026-118178: RSS feed could redirect its subscription to a local file or network share

Status: published. Published: 2026-10-27. Updated: 2026-11-04.

A remote RSS feed could use the itunes:new-feed-url or newLocation element to permanently change its stored subscription URL to a file: URL. Thunderbird then read that location on every feed update. This allowed a malicious feed, or an attacker able to modify a feed delivered over HTTP, to make Thunderbird read local files and, on Windows, connect to an attacker-controlled network share, which could leak the user's NTLM credentials.
The NTLM credential leak only affects Thunderbird on Windows. Other operating systems are affected by the local file read only. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Mozilla / Thunderbird: ≥ 153.6; ≤ 153.* (unaffected, rpm); ≥ 159; ≤ * (unaffected, rpm). Source: CNA: mozilla

## Severity and prioritization

- CVSS 3.1: 5.7 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N; source: ADP: CISA-ADP

- CVSS 3.1: 5.7 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N; source: NVD: 134c704f-9b21-4f2e-91b3-4a467353bcc0

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-04; percentile 7.58%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-829

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=2075772 (CNA: mozilla)

- https://www.mozilla.org/security/advisories/mfsa2026-121/ (CNA: mozilla)

- https://www.mozilla.org/security/advisories/mfsa2026-122/ (CNA: mozilla)

- https://bugzilla.mozilla.org/show_bug.cgi?id=2075772 (security@mozilla.org)

- https://www.mozilla.org/security/advisories/mfsa2026-121/ (security@mozilla.org)

- https://www.mozilla.org/security/advisories/mfsa2026-122/ (security@mozilla.org)

## Provenance

- CNA: mozilla: https://www.cve.org/CVERecord?id=CVE-2026-118178; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118178; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118178; retrieved 2026-11-04; source updated Not reported

Revision: 43d47e05c0eb8157b9162d24613de2914464bb72c7326cbec239337429c9dce7

Canonical: https://y2.dev/cve/CVE-2026-118178

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