High 8.8Published Sep 29, 2026

CVE-2026-100780Use-after-free in the DOM: Core & HTML component

Updated under an hour ago (Oct 26, 2026, 2:00 PM ET)

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It affects Mozilla Firefox and 1 other product. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.32%, higher than 23% of scored CVEs.

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Exploited in the last 30 days

Use-after-free in the DOM: Core & HTML 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.

CVSS: 8.8 HIGH (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.32% (percentile 23)
Assigned by: mozilla
NVD analysis: Analyzed
Record last updated: Sep 30, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Mozilla Firefox mozilla:firefox (from the name)	115.42 builds before 115.* not affected; 140.17 builds before 140.* not affected; 153.4 builds before 153.* not affected; from 157 not affected	CNA record
Mozilla Thunderbird mozilla:thunderbird (from the name)	140.17 builds before 140.* not affected; 153.4 builds before 153.* not affected; from 157 not affected	CNA record
mozilla firefox mozilla:firefox	before 157.0.0; from 115.1.0 before 115.42.0; from 140.0 before 140.17.0; from 153.0 before 153.4.0	NVD
mozilla thunderbird mozilla:thunderbird	before 157.0; from 140.0 before 140.17.0; from 153.0 before 153.4.0	NVD

References

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2068422	permissions-required
https://www.mozilla.org/security/advisories/mfsa2026-100/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-101/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-102/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-103/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-97/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-98/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-99/	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.