CVE-2026-4720
Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
- State
- Published
- Severity
- 9.8 Critical
- Published
- Mar 24, 2026
- Updated
- Jul 15, 2026
- Reserved
- Mar 23, 2026
Description
Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
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 |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H | redhat-SADP |
Weaknesses
- CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Affected Products
| Product | Versions |
|---|---|
FirefoxMozilla |
|
ThunderbirdMozilla |
|
References
- Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
- https://www.mozilla.org/security/advisories/mfsa2026-20/
- https://www.mozilla.org/security/advisories/mfsa2026-22/
- https://www.mozilla.org/security/advisories/mfsa2026-23/
- https://www.mozilla.org/security/advisories/mfsa2026-24/
- https://access.redhat.com/security/cve/CVE-2026-4720vdb-entry
- RHBZ#2450751issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4720.json
- https://access.redhat.com/errata/RHSA-2026:8427vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7843vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8315vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:5931vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:6342vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:5932vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:6917vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7840vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8285vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7858vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8850vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7842vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8289vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7838vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8288vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7839vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8286vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7841vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8287vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7845vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8290vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7837vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8284vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:5930vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:6188vendor-advisory
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