CVE-2026-100757 Affecting firefox-esr package, versions <153.4.0esr-1
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-DEBIANUNSTABLE-FIREFOXESR-20266106
- published30 Sept 2026
- disclosed29 Sept 2026
Introduced: 29 Sep 2026
NewCVE-2026-100757 (opens in a new tab)How to fix?
Upgrade Debian:unstable firefox-esr to version 153.4.0esr-1 or higher.
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:unstable relevant fixed versions and status.
Use-after-free in the Widget component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
References
- https://security-tracker.debian.org/tracker/CVE-2026-100757
- https://bugzilla.mozilla.org/show_bug.cgi?id=2049352
- https://www.mozilla.org/security/advisories/mfsa2026-100/
- https://www.mozilla.org/security/advisories/mfsa2026-97/
- https://www.mozilla.org/security/advisories/mfsa2026-98/
- https://www.mozilla.org/security/advisories/mfsa2026-99/
- https://www.mozilla.org/security/advisories/mfsa2026-101/
- https://www.mozilla.org/security/advisories/mfsa2026-102/
- https://www.mozilla.org/security/advisories/mfsa2026-103/