CVE-2026-16377

Mitigation bypass in the PDF Viewer component

State: Published
Severity: 9.8 Critical
Published: Jul 21, 2026
Updated: Jul 22, 2026
Reserved: Jul 20, 2026

Description

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

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-693 Protection Mechanism Failure

Affected Products

Product	Versions
FirefoxMozilla	140.13 through 140.*Not affected 153 and laterNot affected
ThunderbirdMozilla	140.13 through 140.*Not affected 153 and laterNot affected

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/

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