Out-of-bounds write in MongoDB Server - CVE-2026-18693
Published: August 18, 2026
Vulnerability identifier: #VU144136
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-18693
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service or disclose limited memory contents.
The vulnerability exists due to out-of-bounds write in MongoDB Server timeseries bucket handling when processing certain document insertions into timeseries collections. A remote user can insert crafted documents to cause a denial of service or disclose limited memory contents.
Exploitation requires write privileges on timeseries collections, and the issue is triggered by a subsequent insert into the affected bucket after the internal data structure becomes inconsistent.
Affected software
MongoDB Server
How to mitigate CVE-2026-18693
Install security update from vendor's website.
MongoDB Server - addressed in versions 7.0.40, 8.0.29, 8.3.8