Reachable assertion in MongoDB Server - CVE-2026-9748
Published: August 18, 2026
Vulnerability identifier: #VU144166
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-9748
CWE-ID: CWE-617
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 reachable assertion in $_internalConvertBucketIndexStats and TeeBuffer when processing an aggregation pipeline that places $_internalConvertBucketIndexStats before $facet. A remote user can send a specially crafted request to cause a denial of service.
The issue is triggered when index stats conversion fails and the stage propagates an unexpected PauseExecution signal upstream to $facet coordination logic.
Affected software
MongoDB Server
How to mitigate CVE-2026-9748
Install security update from vendor's website.
MongoDB Server - addressed in versions 7.0.35, 8.0.10, 8.2.10, 8.3.3