9.1

CVE-2025-6427: mozilla firefox Protection Mechanism Failure

CVSS: 9.1v3.1CriticalModified
AliasesUBUNTU-CVE-2025-6427CGA-9hhq-v2vg-6qrrCGA-rh9g-xp5x-qmw6
Published 24-06-2025Last modified 13-04-2026
Open JSON

Vulnerability summary

CVE-2025-6427 is a critical (CVSS 9.1) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.2% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.37%
0%100%
Low · +0.03 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

An attacker was able to bypass the `connect-src` directive of a Content Security Policy by manipulating subdocuments. This would have also hidden the connections from the Network tab in Devtools. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.37%

Chance of exploitation in the next 30 days

Percentile

29%

Versus all other CVEs

30-day change

+0.03 pp

From 0.34% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.37%

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