CVE-2025-6436

Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 140.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
6.5 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
mozillaCNA
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CISA-ADPADP
6.5 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
140.0-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
not-affected
mozjs102
plucky
dne
oracular
dne
noble
ignored
jammy
ignored
mozjs115
plucky
ignored
oracular
ignored
noble
ignored
jammy
dne
mozjs38
plucky
dne
oracular
dne
noble
dne
jammy
dne
bionic
needs-triage
mozjs52
plucky
dne
oracular
dne
noble
dne
jammy
dne
focal
ignored
bionic
ignored
mozjs68
plucky
dne
oracular
dne
noble
dne
jammy
dne
focal
ignored
mozjs78
plucky
dne
oracular
dne
noble
dne
jammy
ignored
mozjs91
plucky
dne
oracular
dne
noble
dne
jammy
ignored
thunderbird
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
needed
Vulnerability Media Exposure
References
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764
https://www.mozilla.org/security/advisories/mfsa2025-51/