Use-after-free in MongoDB Server - CVE-2026-8336
Published: August 18, 2026
Vulnerability identifier: #VU144156
CSH Severity: Low
CVSS v4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-8336
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to use-after-free in $_internalJsEmit and mapreduce commands when invoking $_internalJsEmit or the mapreduce command's map function in a certain way and subsequently using the server-side JavaScript engine. A remote user can invoke these command paths in a crafted sequence to cause a denial of service.
The issue is triggered when server-side JavaScript features such as $where, $function, or the mapreduce reduce stage are later used in a specific way.
Affected software
MongoDB Server
How to mitigate CVE-2026-8336
Install security update from vendor's website.
MongoDB Server - addressed in versions 8.2.9, 8.3.2