CVE-2026-6755 json
Mitigation bypass in the DOM: postMessage component
published 2026-04-21 6 mo ago modified 2026-10-26 14 d ago also EUVD-2026-24096
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 16%
- public exploits
- 0
- none known
Summary
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
Patch / fix
- mozilla firefox 150
- mozilla firefox_esr 150
- mozilla thunderbird 150
- mozilla thunderbird_esr 150
- firefox-esr openSUSE Tumbleweed 153.0-1.1
- MozillaFirefox openSUSE Tumbleweed 150.0-1.1
opensuse advisories openSUSE-SU-2026:11373-1openSUSE-SU-2026:10626-1
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-6755 updated cvss 6.1
firefox: thunderbird: Mitigation bypass in the DOM: postMessage component
-
Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 firefox, thunderbird Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird Red Hat Enterprise Linux 10 firefox, thunderbird, rhel10/firefox-flatpak, rhel10/thunderbird-flatpaknot affected: vulnerable code not present
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 6 mo ago
Exploit prediction
0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected products
- Mozilla Firefox
- Mozilla Thunderbird
Classification
- Weakness
-
- CWE-352 Cross-Site Request Forgery
References
-
mozilla.org
/security/advisories/mfsa2026-30/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-33/
vendor-advisory
-
bugzilla.mozilla.org
/show_bug.cgi?id=1880429
permissions-required
Sources
- CVE List CVE-2026-6755
- NVD CVE-2026-6755
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.