CVE-2026-16377criticalCWE-693

CVE-2026-16377: critical vulnerability in Mozilla Firefox

Mitigation bypass in the PDF Viewer component

Published 21 Jul 2026 · Updated 22 Jul 2026

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28Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 9.8epss 0.6%

Mitigation bypass in the PDF Viewer component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=2037770 https://www.mozilla.org/security/advisories/mfsa2026-68/https://www.mozilla.org/security/advisories/mfsa2026-70/https://www.mozilla.org/security/advisories/mfsa2026-71/https://www.mozilla.org/security/advisories/mfsa2026-72/