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VulnerabilityPublished Updated

CVE-2026-124903: Mozjs52 · Sandbox escape due to use-after-free in the IPC component

Affects mozjs52Source GCVE Database

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Authoritative record:CVE-2026-124903· Critical 9.6

Not known to be exploited · CVSS 9.6 Critical.

Data as of 13 Nov 2026, 22:47 UTC

CVSS 3.1 base score
9.6Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.19.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSmozjs102pkg:deb/ubuntu/mozjs102?arch=source&distro=nobleOther threatsAffected
  • =102.15.1-1
  • =102.15.1-3ubuntu2
Fixed in–
Ubuntu 24.04 LTSmozjs115pkg:deb/ubuntu/mozjs115?arch=source&distro=nobleOther threatsAffected
  • 115.3.0-0ubuntu1 – 115.10.0-1
9 affected builds
Fixed in–
Ubuntu 22.04 LTSmozjs102pkg:deb/ubuntu/mozjs102?arch=source&distro=jammyOther threatsAffected
  • 102.11.0-0ubuntu0.22.04.1 – 102.15.1-0ubuntu0.22.04.1
4 affected builds
Fixed in–
Ubuntu 22.04 LTSmozjs78pkg:deb/ubuntu/mozjs78?arch=source&distro=jammyOther threatsAffected
  • =78.13.0-1
  • =78.15.0-2
  • =78.15.0-4ubuntu1
Fixed in–
Ubuntu 22.04 LTSmozjs91pkg:deb/ubuntu/mozjs91?arch=source&distro=jammyOther threatsAffected
  • 91.5.1-0ubuntu1 – 91.10.0-0ubuntu1
5 affected builds
Fixed in–
Ubuntu 22.04 LTSthunderbirdpkg:deb/ubuntu/thunderbird?arch=source&distro=jammyOther threatsAffected
  • 1:91.1.2+build1-0ubuntu1 – 1:140.7.1+build1-0ubuntu0.22.04.1
39 affected builds
Fixed in–

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AI-suggested

This vulnerability is fixed in Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7, Thunderbird 160, and Thunderbird 153.7. Users and administrators should apply these official updates promptly to remediate the issue. No additional mitigations are indicated by the vendor advisory.

Description

CVE-2026-124903 is a critical use-after-free vulnerability in the IPC component of mozjs52 that allows sandbox escape. This flaw was fixed in Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7, Thunderbird 160, and Thunderbird 153.7. The vulnerability has a high CVSS score of 9.6, indicating it can be exploited remotely without privileges and causes complete confidentiality, integrity, and availability impact. No known exploits in the wild have been reported. Multiple specific vulnerable versions of mozjs52 are identified.

References

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