Vulnerability in Mozilla Firefox
CVE-2025-2857
Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was being exploited in the wild. *This only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.019 (79.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: +0.000
Affected products
- Mozilla Firefox — versions 115.21.1, 128.8.1, 136.0.4
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- issues.chromium.org/issues/405143032 (Permissions Required)
- www.cve.org/CVERecord (Third Party Advisory)
- www.mozilla.org/security/advisories/mfsa2025-19/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-2857?
- CVE-2025-2857 is a critical-severity vulnerability in Mozilla Firefox, classified under Exposure of Resource to Wrong Sphere. CVSS score: 10.0/10. Published 2025-03-27.
- How severe is CVE-2025-2857?
- Critical severity. CVSS v3 base score is 10.0 out of 10.
- Is CVE-2025-2857 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.