Risk Scores
CVSS v3.1
9.800000190734863
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla Foundation | Mozilla Firefox ESR |
Timeline
- Apr 7, 2026 CVE Published
=========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2026.3333 MFSA 2026-26 Security Vulnerabilities fixed in Firefox ESR 115.34.1 8 April 2026 =========================================================================== AUSCERT Security Bulletin Summary --------------------------------- Product: Mozilla Firefox ESR Publisher: Mozilla Foundation Operating System: Windows Linux macOS Resolution: Patch/Upgrade CVE Names: CVE-2026-5731 Original Bulletin: https://www.mozilla.org/en-US/security/advisories/mfsa2026-26/ Comment: CVSS (Max): 9.8 CVE-2026-5731 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) CVSS Source: CISA-ADP Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H EPSS (Max): None available when published - --------------------------BEGIN INCLUDED TEXT-------------------- Mozilla Foundation Security Advisory 2026-26 Security Vulnerabilities fixed in Firefox ESR 115.34.1 Announced: April 7, 2026 Impact: low Products: Firefox ESR Fixed in: Firefox ESR 115.34.1 # CVE-2026-5731: Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 Reporter: Brian Grinstead, Christian Holler, Tom Schuster and the Mozilla Fuzzing Team Impact: high 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. References o Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 - --------------------------END INCLUDED TEXT---------------------- You have received this e-mail bulletin as a result of your organisation's registration with AUSCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AUSCERT's members. As AUSCERT did not write the document quoted above, AUSCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AUSCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://portal.auscert.org.au/bulletins/ =========================================================================== AUSCERT The University of Queensland, Brisbane QLD 4072 Australia e: auscert@auscert.org.au t: +61 (0)7 3365 4417 Allies in Cyber Security ===========================================================================
| Vendor | Product | Versions |
|---|---|---|
| Mozilla Foundation | Mozilla Firefox ESR |