Reachable assertion in MongoDB Server - CVE-2026-18697
Published: August 18, 2026
Vulnerability identifier: #VU144137
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-18697
CWE-ID: CWE-617
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to reachable assertion in MongoDB Server aggregation framework on mongos when processing a specially formed aggregation command. A remote attacker can submit a specially formed aggregation command to cause a denial of service.
The issue causes the mongos router process to terminate unexpectedly, disrupting client connections routed through the affected instance.
Affected software
MongoDB Server
How to mitigate CVE-2026-18697
Install security update from vendor's website.
MongoDB Server - addressed in versions 7.0.40, 8.0.29, 8.3.8