CVE-2026-106429: CWE-191: Integer Underflow (Wrap or Wraparound) in MongoDB libmongocrypt
Description
CVE-2026-106429 is an integer underflow vulnerability in the KMS endpoint-parsing logic of MongoDB libmongocrypt. It can cause an allocation failure that terminates the application process. This occurs when an authenticated user modifies a key document in the key vault collection or when an application accepts a KMS endpoint containing a colon after its path or query during key creation. The vulnerability does not result in memory access outside allocated bounds.
CVSS v4.0
Score 7.1high
Affected software
MongoDB
libmongocrypt
pkg:github/mongodb/libmongocryptRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves an integer underflow in libmongocrypt's KMS endpoint-parsing logic. The underflow leads to an allocation failure that causes the application process to terminate unexpectedly. The flaw can be triggered by an authenticated user modifying a key document in the key vault collection or by processing a KMS endpoint with a colon after its path or query during key creation. Importantly, the issue does not lead to out-of-bounds memory access.
Potential Impact
The impact is a denial of service due to application process termination caused by allocation failure. There is no indication of memory corruption or unauthorized memory access. The vulnerability requires authenticated user interaction or specific KMS endpoint input.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided at this time. Until a patch is available, avoid accepting KMS endpoints with colons after the path or query and restrict authenticated user modifications to key documents in the key vault collection where possible.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mongodb
- Date Reserved
- 2026-10-06T16:40:35.016Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ac7feee2cdf04f656318bf2
Added to database: 10/08/2026, 20:37:02 UTC
Last enriched: 10/08/2026, 21:03:33 UTC
Last updated: 10/09/2026, 00:08:14 UTC
Views: 8
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