4.3

CVE-2025-6434: mozilla firefox

CVSS: 4.3v3.1MediumModified
AliasesUBUNTU-CVE-2025-6434CGA-gh38-9w53-cvxfCGA-mgvh-84hg-ccrp
Published 24-06-2025Last modified 13-04-2026
Open JSON

Vulnerability summary

CVE-2025-6434 is a medium (CVSS 4.3) vulnerability in mozilla firefox. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.5% of scored vulnerabilities.

Overall risk
17/100
0100
Low · default modelHow is this calculated?
CVSS score
4.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.28%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 6 · Related 8
OPENSUSE-SU-2025:15325-1OPENSUSE-SU-2025:15371-1OPENSUSE-SU-2025:15383-1SUSE-SU-2025:02339-1SUSE-SU-2025:02529-1SUSE-SU-2025:02546-1

Timeline

  1. 24-06-2025
    PublishedVulnerability first disclosed.
  2. 13-04-2026
    Last modifiedVulnerability information updated.

Description

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 was fixed in Firefox 140 and Thunderbird 140.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.28%

Chance of exploitation in the next 30 days

Percentile

20%

Versus all other CVEs

30-day change

+0.02 pp

From 0.26% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.28%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu8 products
  • mozjs102All versions (No fix recorded)
  • mozjs115All versions (No fix recorded)
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
  • mozjs68All versions (No fix recorded)
Chainguard2 products
  • firefox< 140-r0
  • firefox-esr< 140-r0
Mozilla1 product
Wolfi1 product
  • firefox< 140-r0

4 vendors · 12 products

References

7 links