Buffer overflow in Mozilla Firefox
CVE-2026-12297
Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (30.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 30.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Mozilla Firefox — versions 115.37, 140.12, 152
- Mozilla Thunderbird — versions 140.12, 152
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-57/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-58/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-59/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-60/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-61/ (Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-12297?
- CVE-2026-12297 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.6/10. Published 2026-06-16.
- How severe is CVE-2026-12297?
- Critical severity. CVSS v3 base score is 9.6 out of 10.