Mozjs52: [Unknown description] (CVE-2026-84142)
Description
CVE-2026-84142 is a moderate severity vulnerability involving internally found bugs in Firefox 154 that were fixed in Firefox 155. These bugs showed evidence of memory corruption or other security-relevant defects that could potentially be exploited with sufficient effort. The vulnerability affects multiple specific versions of the mozjs52 package as used in various Ubuntu LTS releases. No known exploits are reported in the wild. The vulnerability was addressed by Mozilla in Firefox 155.
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-2026-84142 refers to a set of internally discovered bugs in Firefox 154, including memory corruption and other security-relevant defects. These bugs were fixed in Firefox 155. The vulnerability affects the mozjs52 JavaScript engine component across many specific Ubuntu package versions. Mozilla's advisory groups this issue with other vulnerabilities fixed in Firefox 155, noting moderate impact and the potential for exploitation if sufficient effort is applied. No detailed technical description is provided beyond this general characterization.
Potential Impact
The vulnerability could lead to security issues stemming from memory corruption or other defects, potentially allowing exploitation. However, no active exploits are known. The impact is assessed as moderate by Mozilla, indicating a meaningful but not critical risk if exploited.
Mitigation Recommendations
A fix is available in Firefox 155. Users and administrators should upgrade to Firefox 155 or later to remediate this vulnerability. Since this is not a cloud service, manual patching or upgrading is required. No additional mitigation steps are specified by the vendor.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-84142
- 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: 6a9c2593acd9273b49fbb1b3
Added to database: 09/05/2026, 14:22:11 UTC
Last enriched: 09/07/2026, 15:09:07 UTC
Last updated: 10/18/2026, 18:48:24 UTC
Views: 45
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