CVE-2026-4690

EUVD-2026-14804
Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
Classic Buffer Overflow
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8.6 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CISA-ADPADP
9.6 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Affected Products (NVD)
VendorProductVersion
mozillafirefox_esr
𝑥
< 115.34.0
mozillafirefox
𝑥
< 149.0
mozillafirefox_esr
128.0 ≤
𝑥
< 140.9.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
vulnerable
firefox-esr
bookworm
vulnerable
bookworm (security)
140.9.0esr-1~deb12u1
fixed
bullseye
vulnerable
bullseye (security)
vulnerable
forky
vulnerable
sid
140.9.0esr-1
fixed
trixie
vulnerable
trixie (security)
140.9.0esr-1~deb13u1
fixed
thunderbird
bookworm
vulnerable
bookworm (security)
vulnerable
bullseye
vulnerable
bullseye (security)
vulnerable
forky
vulnerable
sid
1:140.9.0esr-1
fixed
trixie
vulnerable
trixie (security)
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
jammy
not-affected
noble
not-affected
questing
not-affected
thunderbird
jammy
needed
noble
not-affected
questing
not-affected
mozjs38
bionic
needs-triage
jammy
dne
noble
dne
questing
dne
mozjs52
bionic
ignored
focal
ignored
jammy
dne
noble
dne
questing
dne
mozjs68
focal
ignored
jammy
dne
noble
dne
questing
dne
mozjs78
jammy
ignored
noble
dne
questing
dne
mozjs91
jammy
ignored
noble
dne
questing
dne
mozjs102
jammy
ignored
noble
ignored
questing
dne
mozjs115
jammy
dne
noble
ignored
questing
dne