Integer overflow in Mozilla Firefox
Priority MEDIUM 40CWE-190Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-190 and the CVSS impact.
Summary
Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00583 48th percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 140.11, 151Thunderbird (Mozilla): 140.11, 151
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mozilla | Firefox | — | 140.11, 151 | Patch available | CNA |
| Mozilla | Thunderbird | — | 140.11, 151 | Patch available | CNA |
- Firefox VendorMozilla Affected — Fixed in 140.11, 151 Patch available CNA
- Thunderbird VendorMozilla Affected — Fixed in 140.11, 151 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:* | before 140.11.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* | before 151.0.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:* | before 140.11 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 151.0.0 | Vulnerable | Mozilla |
- cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:* Versions before 140.11.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* Versions before 151.0.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:* Versions before 140.11 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 151.0.0 Vulnerable ·Mozilla
Remediation
- Fix · CNA Firefox (Mozilla) Fixed in 140.11, 151
- Fix · CNA Thunderbird (Mozilla) Fixed in 140.11, 151
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-8949
- 2026-10-03 Alias added: GHSA-wpxg-v53p-m79m
References
More Mozilla Firefox vulnerabilities
- TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
- TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
- TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
- TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
- TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
- TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2026-8949 · CVE Program
- CVE-2026-8949 · NVD
- FIRST EPSS
- GHSA-wpxg-v53p-m79m · GitHub Advisory Database · CC BY 4.0
- CVE-2026-8949 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences