CVE-2026-117966 Affecting firefox-esr package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-FIREFOXESR-21757700
- published28 Oct 2026
- disclosed27 Oct 2026
Introduced: 27 Oct 2026
NewCVE-2026-117966 (opens in a new tab)How to fix?
There is no fixed version for Debian:12 firefox-esr.
NVD Description
Note: Versions mentioned in the description apply only to the upstream firefox-esr package and not the firefox-esr package as distributed by Debian.
See How to fix? for Debian:12 relevant fixed versions and status.
Site isolation issue in the Networking: HTTP component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
References
- https://security-tracker.debian.org/tracker/CVE-2026-117966
- https://bugzilla.mozilla.org/show_bug.cgi?id=2075726
- https://www.mozilla.org/security/advisories/mfsa2026-118/
- https://www.mozilla.org/security/advisories/mfsa2026-119/
- https://www.mozilla.org/security/advisories/mfsa2026-120/
- https://www.mozilla.org/security/advisories/mfsa2026-121/
- https://www.mozilla.org/security/advisories/mfsa2026-122/