CVE-2026-109783: Mozjs52 · Mitigation bypass in the File Handling component
Affects mozjs52Source GCVE Database
Not known to be exploited · CVSS 8.3 High · fixed in 153.5 : patch mozjs52 soon.
Data as of 28 Oct 2026, 01:29 UTC
- Patch
- Available – fixed in 153.5
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSmozjs102pkg:deb/ubuntu/mozjs102?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSmozjs115pkg:deb/ubuntu/mozjs115?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSmozjs102pkg:deb/ubuntu/mozjs102?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSmozjs78pkg:deb/ubuntu/mozjs78?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSmozjs91pkg:deb/ubuntu/mozjs91?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSthunderbirdpkg:deb/ubuntu/thunderbird?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available and has been released in Firefox ESR 153.5 and Thunderbird 153.5. Users and administrators should update to these versions or later to remediate this vulnerability. No additional mitigation actions are indicated by the vendor advisory.
Description
CVE-2026-109783 is a high-severity mitigation bypass vulnerability in the File Handling component of mozjs52. This flaw was addressed and fixed in Firefox ESR version 153.5 and Thunderbird 153.5. The vulnerability could allow an attacker to bypass security mitigations, potentially leading to significant impact on confidentiality, integrity, and availability.
References
- ubuntu.com/security/CVE-2026-109783 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-109783 (opens in a new tab)
- mozilla.org/en-US/security/advisories/mfsa2026-108/ (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=2075533 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-108/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-110/ (opens in a new tab)