CVE-2026-6763

MEDIUM 6.5

Mitigation bypass in the File Handling component

CVSS Score

6.5

EPSS Score

0.1%

EPSS Percentile

19th

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Vendor	mozilla
Product	firefox
Ecosystems	Browser JavaScript
Industries	Technology
Published	Apr 21, 2026
Last Updated	May 26, 2026

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Affected Versions

Mozilla / Firefox

All versions affected

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=2021666 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-30/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-32/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-33/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-34/

Credits

Tomoya Nakanishi