CVE-2026-4691

CRITICAL

Use-after-free in the CSS Parsing and Computation component

Title source: cna
STIX 2.1

Description

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

References (6)

Scores

CVSS v3 9.8
EPSS 0.0004
EPSS Percentile 11.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-416
Status published
Products (12)
mozilla/firefox < 115.34.0
mozilla/firefox < 149.0
Mozilla/Firefox 115.34 - 115.*
Mozilla/Firefox 140.9 - 140.*
Mozilla/Firefox 149
Mozilla/Firefox unspecified - 149
Mozilla/Firefox ESR unspecified - 115.34
Mozilla/Firefox ESR unspecified - 140.9
Mozilla/Thunderbird 140.9 - 140.*
Mozilla/Thunderbird 149
... and 2 more
Published Mar 24, 2026
Tracked Since Mar 24, 2026