CVE-2026-109705: Mozjs52 · Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free
Affects mozjs52Source GCVE Database
Not known to be exploited · CVSS 9.6 Critical.
Data as of 29 Oct 2026, 00:13 UTC
CVSS:3.1/AV:N/AC:L/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
This vulnerability has been fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5. Users and administrators should apply these updates to remediate the issue. No additional mitigation steps are required beyond applying the official patches.
Description
CVE-2026-109705 is a critical vulnerability in the mozjs52 component affecting Firefox, Firefox ESR, and Thunderbird. It involves a sandbox escape and site isolation issue caused by incorrect boundary conditions and a use-after-free flaw in the Networking component. This vulnerability allows an attacker to potentially bypass sandbox restrictions, leading to high impact on confidentiality, integrity, and availability. The issue was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
References
- ubuntu.com/security/CVE-2026-109705 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-109705 (opens in a new tab)
- mozilla.org/en-US/security/advisories/mfsa2026-106/ (opens in a new tab)
- mozilla.org/en-US/security/advisories/mfsa2026-108/ (opens in a new tab)
- mozilla.org/en-US/security/advisories/mfsa2026-109/ (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=2040905 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-106/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-108/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-109/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-110/ (opens in a new tab)