CVE-2025-6434

EUVD-2025-21375
The exception page for the HTTPS-Only feature, displayed when a website is opened via HTTP, lacked an anti-clickjacking delay, potentially allowing an attacker to trick a user into granting an exception and loading a webpage over HTTP. This vulnerability affects Firefox < 140 and Thunderbird < 140.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
4.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CISA-ADPADP
4.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 8%
Affected Products (NVD)
VendorProductVersion
mozillafirefox
𝑥
< 140.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
147.0.4-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
jammy
not-affected
noble
not-affected
oracular
not-affected
plucky
not-affected
questing
not-affected
thunderbird
jammy
Fixed 1:140.7.1+build1-0ubuntu0.22.04.1
released
noble
not-affected
oracular
not-affected
plucky
not-affected
questing
not-affected
mozjs38
bionic
needs-triage
jammy
dne
noble
dne
oracular
dne
plucky
dne
questing
dne
mozjs52
bionic
ignored
focal
ignored
jammy
dne
noble
dne
oracular
dne
plucky
dne
questing
dne
mozjs68
focal
ignored
jammy
dne
noble
dne
oracular
dne
plucky
dne
questing
dne
mozjs78
jammy
ignored
noble
dne
oracular
dne
plucky
dne
questing
dne
mozjs91
jammy
ignored
noble
dne
oracular
dne
plucky
dne
questing
dne
mozjs102
jammy
ignored
noble
ignored
oracular
dne
plucky
dne
questing
dne
mozjs115
jammy
dne
noble
ignored
oracular
ignored
plucky
ignored
questing
dne
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/show_bug.cgi?id=1955182
https://www.mozilla.org/security/advisories/mfsa2025-51/
https://www.mozilla.org/security/advisories/mfsa2025-54/