Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
CVE-2026-8955
HIGHNVD 8.86.5▼
EchelonGraph scoreHIGH confidence
Score 6.5 from GitHub Security Advisory published 2026-05-19. NVD baseline CVSS 6.5; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, nvd
8.8
- CVSS v3
- 8.8
- EG Score
- 6.5(high)
- EPSS
- 12.5%
- KEV
- Not listed
Published
May 19, 2026
Last Modified
May 20, 2026
References (5)
- security@mozillahttps://bugzilla.mozilla.org/show_bug.cgi?id=2031064
- security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-46/
- security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-48/
- security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-50/
- security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-51/
Frequently asked(5)
What is CVE-2026-8955?
CVE-2026-8955 is a high vulnerability published on May 19, 2026. Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
When was CVE-2026-8955 disclosed?
CVE-2026-8955 was first published in the National Vulnerability Database on May 19, 2026, with the most recent update on May 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8955 actively exploited?
CVE-2026-8955 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8955?
CVE-2026-8955 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 6.5.
How do I remediate CVE-2026-8955?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8955, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-8955
Is Your Infrastructure Affected by CVE-2026-8955?
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