6.5

CVE-2026-6755: Mitigation bypass in the DOM: postMessage component

Analyzed
AliasesUBUNTU-CVE-2026-6755CGA-84xf-jvwf-fhpxCGA-wq66-38g4-q573
Published 21-04-2026Last modified 27-05-2026

Vulnerability summary

CVE-2026-6755 is a medium (CVSS 6.5) Cross-Site Request Forgery (CSRF) vulnerability in mozilla firefox. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 15.2% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.25%
0%100%
Low · +0.06 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:10626-1OPENSUSE-SU-2026:11373-1CGA-CQ89-X9MX-JFMH

Timeline

  1. 21-04-2026
    PublishedVulnerability first disclosed.
  2. 27-05-2026
    Last modifiedVulnerability information updated.

Description

Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.25%

Chance of exploitation in the next 30 days

Percentile

15%

Versus all other CVEs

30-day change

Increase +0.06 pp

From 0.19% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

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)
Mozilla2 products
Chainguard1 product
  • firefox< 150-r0
Wolfi1 product
  • firefox< 150-r0

4 vendors · 12 products

References

6 links