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
Summary
| CVE | CVE-2026-5731 |
|---|---|
| State | PUBLISHED |
| Assigner | mozilla |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-07 13:16:47 UTC |
| Updated | 2026-07-15 01:16:43 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 9.8 CRITICAL from ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.003400000 probability, percentile 0.261680000 (date 2026-07-16)
Problem Types: CWE-119 | CWE-787 | CWE-119 CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer | CWE-787 Out-of-bounds Write
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Mozilla | Firefox | 115.34.0 | All | All | All |
| Application | Mozilla | Firefox | 140.9.0 | All | All | All |
| Application | Mozilla | Firefox | 149.0.1 | All | All | All |
| Application | Mozilla | Thunderbird | 140.9.0 | All | All | All |
| Application | Mozilla | Thunderbird | 149.0.1 | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Mozilla | Firefox | unaffected 115.34.1 115.* rpm | Not specified |
| CNA | Mozilla | Firefox | unaffected 140.9.1 140.* rpm | Not specified |
| CNA | Mozilla | Firefox | unaffected 149.0.2 * rpm | Not specified |
| CNA | Mozilla | Thunderbird | unaffected 140.9.1 140.* rpm | Not specified |
| CNA | Mozilla | Thunderbird | unaffected 149.0.2 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | unaffected 0:140.9.1-1.el10_1 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | unaffected 0:140.9.1-1.el10_1 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | unaffected 0:140.9.1-1.el10_0 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | unaffected 0:140.9.1-1.el10_0 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 Extended Lifecycle Support | unaffected 0:140.9.1-2.el7_9 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | unaffected 0:140.9.1-1.el8_10 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | unaffected 0:140.9.1-1.el8_10 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.2 Advanced Update Support | unaffected 0:140.9.1-1.el8_2 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | unaffected 0:140.9.1-1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | unaffected 0:140.9.1-1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | unaffected 0:140.9.1-1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | unaffected 0:140.9.1-1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Telecommunications Update Service | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Telecommunications Update Service | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | unaffected 0:140.9.1-1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | unaffected 0:140.9.1-1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | unaffected 0:140.9.1-1.el9_7 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | unaffected 0:140.9.1-1.el9_7 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.0 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el9_0 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.0 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el9_0 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el9_2 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions | unaffected 0:140.9.1-1.el9_2 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.4 Extended Update Support | unaffected 0:140.9.1-1.el9_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.4 Extended Update Support | unaffected 0:140.9.1-1.el9_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | unaffected 0:140.9.1-1.el9_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | unaffected 0:140.9.1-1.el9_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/errata/RHSA-2026:9345 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13922 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:8459 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:15889 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:12264 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:7671 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-5731 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:11805 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13683 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13342 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13582 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13533 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:14303 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| bugzilla.mozilla.org/buglist.cgi | [email protected] | bugzilla.mozilla.org | Broken Link |
| access.redhat.com/errata/RHSA-2026:8052 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13412 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5731.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:9638 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.mozilla.org/security/advisories/mfsa2026-29 | [email protected] | www.mozilla.org | Vendor Advisory |
| www.mozilla.org/security/advisories/mfsa2026-28 | [email protected] | www.mozilla.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:13600 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13583 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.mozilla.org/security/advisories/mfsa2026-26 | [email protected] | www.mozilla.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:14223 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.mozilla.org/security/advisories/mfsa2026-27 | [email protected] | www.mozilla.org | Vendor Advisory |
| www.mozilla.org/security/advisories/mfsa2026-25 | [email protected] | www.mozilla.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:13977 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:7672 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:11813 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13596 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13665 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13682 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Brian Grinstead, Christian Holler, Tom Schuster and the Mozilla Fuzzing Team (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-04-07T13:01:15.389Z | Reported to Red Hat. |
| ADP | 2026-04-07T12:43:11.895Z | Made public. |
Solutions
ADP: RHSA-2026:13977: Red Hat Enterprise Linux Server (v. 7 ELS)
ADP: RHSA-2026:13665: Red Hat Enterprise Linux AppStream EUS (v. 10.0)
ADP: RHSA-2026:11813: Red Hat Enterprise Linux AppStream EUS (v. 10.0)
ADP: RHSA-2026:7672: Red Hat Enterprise Linux AppStream (v. 10)
ADP: RHSA-2026:9638: Red Hat Enterprise Linux AppStream (v. 10)
ADP: RHSA-2026:8052: Red Hat Enterprise Linux AppStream (v. 8)
ADP: RHSA-2026:9345: Red Hat Enterprise Linux AppStream (v. 8)
ADP: RHSA-2026:11805: Red Hat Enterprise Linux AppStream AUS (v. 8.2)
ADP: RHSA-2026:13600: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)
ADP: RHSA-2026:14303: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)
ADP: RHSA-2026:13683: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.6), Red Hat Enterprise Linux AppStream TUS (v.8.6)
ADP: RHSA-2026:15889: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.6), Red Hat Enterprise Linux AppStream TUS (v.8.6)
ADP: RHSA-2026:13682: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)
ADP: RHSA-2026:14223: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)
ADP: RHSA-2026:13596: Red Hat Enterprise Linux AppStream E4S (v.9.0)
ADP: RHSA-2026:12264: Red Hat Enterprise Linux AppStream E4S (v.9.0)
ADP: RHSA-2026:13922: Red Hat Enterprise Linux AppStream E4S (v.9.2)
ADP: RHSA-2026:13412: Red Hat Enterprise Linux AppStream E4S (v.9.2)
ADP: RHSA-2026:13582: Red Hat Enterprise Linux AppStream EUS (v.9.4)
ADP: RHSA-2026:13533: Red Hat Enterprise Linux AppStream EUS (v.9.4)
ADP: RHSA-2026:13583: Red Hat Enterprise Linux AppStream EUS (v.9.6)
ADP: RHSA-2026:13342: Red Hat Enterprise Linux AppStream EUS (v.9.6)
ADP: RHSA-2026:7671: Red Hat Enterprise Linux AppStream (v. 9)
ADP: RHSA-2026:8459: Red Hat Enterprise Linux AppStream (v. 9)