🛡️ CVE-2026-8950 — firefox

🔴 CVSS 9.3 — Critical ✅ No Known Exploit CWE-346 NVD
9.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability none.

Weakness class

CVE-2026-8950 is classified as CWE-346: Origin Validation Error. The origin of a message or request is not verified properly, so one source can pose as another.

Affected software

CVE-2026-8950 is recorded against 3 packages.

  • firefox (fixed in 151.0.0)
  • thunderbird (fixed in 151.0.0)
  • unknown

Timeline and source

Published on 19 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

bugzilla.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org

CVE-2026-8950 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity CRITICAL
CVSS Score 9.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
CWE CWE-346
Public Exploit ✅ No
Source NVD
Published 2026-05-19
Updated 2026-08-11
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
firefox — 151.0.0
thunderbird — 151.0.0
unknown — —

Similar Threats

Exploit Protection

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