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VulnerabilityPublished Updated

CVE-2025-1942: Mozjs52 · When String.toUpperCase() caused a string to get longer it was possible for uninitialized

Affects mozjs52Source GCVE Database

0
Authoritative record:CVE-2025-1942· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in 136.0+build3-0ubuntu0.20.04.1 : patch mozjs52 as a priority.

Data as of 28 Oct 2026, 22:28 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 136.0+build3-0ubuntu0.20.04.1, 1:140.7.1+build1-0ubuntu0.22.04.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Mar 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade the Ubuntu to 136.0+build3-0ubuntu0.20.04.1 (firefox package) or 1:140.7.1+build1-0ubuntu0.22.04.1 (thunderbird package).

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
  • <1:140.7.1+build1-0ubuntu0.22.04.1
Fixed in
  • 1:140.7.1+build1-0ubuntu0.22.04.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

When String.toUpperCase() caused a string to get longer it was possible for uninitialized memory to be incorporated into the result string. This vulnerability was fixed in Firefox 136 and Thunderbird 136.

References

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