CVE-2026-5731

9.8 CRITICAL
Published: April 07, 2026 Modified: April 13, 2026
View on NVD

Description

Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2021894%2C2022225%2C2022252%2C2022294%2C2023007%2C2023130%2C2023191%2C2023364%2C2023829%2C2024074%2C2024417%2C2024433%2C2024436%2C2024437%2C2024453%2C2024461%2C2024462%2C2024472%2C2024474%2C2024477%2C2025364%2C2025401%2C2025402%2C2025472%2C2026287%2C2026299%2C2026305%2C2026426
Source: security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-25/
Source: security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-26/
Source: security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-27/
Source: security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-28/
Source: security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-29/
Source: security@mozilla.org

6 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.8 / 10.0
EPSS (Exploit Probability)
0.1%
22th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

CWE-119

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