VulnerabilityAnalyzed
CVE-2026-100821
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.
MEDIUM 4.7EPSS 0.14%
Does this matter?
Lower severity and a low EPSS score (0.14%). Track it; it rarely justifies an emergency change on its own.
Description
Site isolation issue in the Panning and Zooming 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 3.1
- 4.7 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
- EPSS
- 0.14% probability · 4th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-346
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS moved from 0.2% on 30 September 2026 to 0.1% on 27 October 2026.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2071784Permissions 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.