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 affects Firefox < 136.0.4, Firefox ESR < 128.8.1, and Firefox ESR < 115.21.1.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
10 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
mozillaCNA
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CISA-ADPADP
10 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 27%
VendorProductVersion
mozillafirefox
𝑥
< 136.0.4
mozillafirefox
𝑥
< 115.21.1
mozillafirefox
128.1.0 ≤
𝑥
< 128.8.1
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
139.0-1
fixed
firefox-esr
bullseye
115.14.0esr-1~deb11u1
fixed
bullseye (security)
128.11.0esr-1~deb11u1
fixed
bookworm
128.10.0esr-1~deb12u1
fixed
bookworm (security)
128.11.0esr-1~deb12u1
fixed
sid
128.11.0esr-1
fixed
trixie
128.11.0esr-1
fixed
References
https://bugzilla.mozilla.org/show_bug.cgi?id=1956398
https://issues.chromium.org/issues/405143032
https://www.cve.org/CVERecord?id=CVE-2025-2783
https://www.mozilla.org/security/advisories/mfsa2025-19/