CVE-2026-4691

CRITICAL

9.8

Description

Use-after-free in the CSS Parsing and Computation component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

CVE Details

CVSS v3.1 Score9.8

SeverityCRITICAL

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

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published3/24/2026

Last Modified3/26/2026

Sourcenvd

Honeypot Sightings0

Affected Products

mozilla:firefox

Weaknesses (CWE)

CWE-416CWE-416

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2017512(security@mozilla.org)

https://www.mozilla.org/security/advisories/mfsa2026-20/(security@mozilla.org)

https://www.mozilla.org/security/advisories/mfsa2026-21/(security@mozilla.org)

https://www.mozilla.org/security/advisories/mfsa2026-22/(security@mozilla.org)

https://www.mozilla.org/security/advisories/mfsa2026-23/(security@mozilla.org)

https://www.mozilla.org/security/advisories/mfsa2026-24/(security@mozilla.org)

IOC Correlations

No correlations recorded

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