CVE-2025-6434

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
NISTNIST
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
mozillaCNA
---
---
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: 7%
VendorProductVersion
mozillafirefox
𝑥
< 140.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
141.0.3-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
not-affected
thunderbird
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
not-affected
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
mozjs102
plucky
dne
oracular
dne
noble
ignored
jammy
ignored
mozjs115
plucky
ignored
oracular
ignored
noble
ignored
jammy
dne