What’s Vulnerable › Vulnerabilities

CVE-2026-109739: Privilege escalation in the WebExtensions component

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-14
• Weakness: CWE-269

Description

Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2049069
• https://www.mozilla.org/security/advisories/mfsa2026-106/
• https://www.mozilla.org/security/advisories/mfsa2026-109/

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