CVE-2026-6755: Vulnerability in Mozilla Firefox
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
AI Analysis
Technical Summary
CVE-2026-6755 is a vulnerability involving a mitigation bypass in the DOM postMessage component of Mozilla Firefox. The flaw could potentially allow an attacker to circumvent security mitigations related to postMessage handling within the DOM. Mozilla fixed this vulnerability in Firefox 150 as part of a broader security update that addressed multiple issues. The vendor advisory classifies the impact of this specific vulnerability as moderate.
Potential Impact
The vulnerability allows bypassing of mitigation controls in the DOM postMessage component, which could weaken security protections in Firefox. However, the impact is rated moderate by Mozilla, indicating that while the issue is significant, it is not considered critical or high severity. There are no reports of exploitation in the wild.
Mitigation Recommendations
Mozilla has fixed this vulnerability in Firefox 150. Users and administrators should update to Firefox 150 or later to remediate this issue. Since an official fix is available, applying the update is the recommended and effective mitigation.
CVE-2026-6755: Vulnerability in Mozilla Firefox
Description
Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-6755 is a vulnerability involving a mitigation bypass in the DOM postMessage component of Mozilla Firefox. The flaw could potentially allow an attacker to circumvent security mitigations related to postMessage handling within the DOM. Mozilla fixed this vulnerability in Firefox 150 as part of a broader security update that addressed multiple issues. The vendor advisory classifies the impact of this specific vulnerability as moderate.
Potential Impact
The vulnerability allows bypassing of mitigation controls in the DOM postMessage component, which could weaken security protections in Firefox. However, the impact is rated moderate by Mozilla, indicating that while the issue is significant, it is not considered critical or high severity. There are no reports of exploitation in the wild.
Mitigation Recommendations
Mozilla has fixed this vulnerability in Firefox 150. Users and administrators should update to Firefox 150 or later to remediate this issue. Since an official fix is available, applying the update is the recommended and effective mitigation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-04-21T12:40:51.062Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-30/","vendor":"Mozilla"}]
Threat ID: 69e7789c19fe3cd2cdd163c9
Added to database: 4/21/2026, 1:16:12 PM
Last enriched: 4/21/2026, 1:46:40 PM
Last updated: 4/22/2026, 7:30:47 AM
Views: 8
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.