Mozjs52: [Unknown description] (CVE-2026-84136)
Description
CVE-2026-84136 is a security vulnerability affecting multiple specific versions of the mozjs52 JavaScript engine component used in Firefox and related Ubuntu packages. The vulnerability is categorized as low impact and is described as an 'Other issue' in the DOM: Navigation component. It was fixed in Firefox 155 as part of a broader security update addressing multiple internally found bugs. The vulnerability has a high CVSS score of 9.8 but is assessed with low impact by the vendor advisory. There are no known exploits in the wild. Multiple Ubuntu LTS versions are affected by this vulnerability in the listed mozjs52 package versions.
CVSS v3.1
Score 9.8critical
Affected software
pkg:deb/ubuntu/mozjs52?arch=source&distro=bionicpkg:deb/ubuntu/mozjs38?arch=source&distro=bionicpkg:deb/ubuntu/mozjs68?arch=source&distro=focalpkg:deb/ubuntu/mozjs52?arch=source&distro=focalpkg:deb/ubuntu/mozjs102?arch=source&distro=jammypkg:deb/ubuntu/mozjs78?arch=source&distro=jammypkg:deb/ubuntu/mozjs91?arch=source&distro=jammypkg:deb/ubuntu/thunderbird?arch=source&distro=jammypkg:deb/ubuntu/mozjs102?arch=source&distro=noblepkg:deb/ubuntu/mozjs115?arch=source&distro=nobleRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-84136 is an internally found security issue in the DOM: Navigation component of the mozjs52 JavaScript engine used in Firefox and Ubuntu packages. The exact technical details of the vulnerability are not described, but it is classified as an 'Other issue' with low impact. It was fixed in Firefox 155 alongside numerous other security vulnerabilities. The vulnerability affects many specific mozjs52 package versions distributed across Ubuntu 18.04, 20.04, 22.04, and 24.04 LTS releases. The Mozilla Foundation released an advisory indicating the fix is included in Firefox 155. No known exploits have been reported in the wild.
Potential Impact
The vulnerability could potentially allow security-relevant defects in the DOM: Navigation component, but it is assessed as low impact by the vendor. The CVSS score is high (9.8), indicating potential severity if exploited, but the vendor advisory classifies the impact as low for this specific issue. No active exploitation is known. The vulnerability affects confidentiality, integrity, and availability as indicated by the CVSS vector, but the practical impact is considered low based on the advisory.
Mitigation Recommendations
A fix for this vulnerability is available in Firefox 155. Users and administrators should upgrade to Firefox 155 or later to remediate this issue. For Ubuntu users, updating the mozjs52 package to a version that includes the Firefox 155 fixes will mitigate the vulnerability. There are no indications that additional mitigation steps are required beyond applying the official update.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-84136
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6a9c2594acd9273b49fbb28b
Added to database: 09/05/2026, 14:22:12 UTC
Last enriched: 09/07/2026, 14:55:30 UTC
Last updated: 10/19/2026, 18:48:24 UTC
Views: 56
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