Vulnerability in MongoDB libmongocrypt

[ Description ]Official description

An integer underflow in the KMS endpoint-parsing logic of MongoDB libmongocrypt can cause an allocation failure that terminates the application process. This can occur 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 issue does not access memory outside its allocated bounds.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund8 Oct 2026WID-SEC-2026-3830

  MongoDB Treiber: Multiple vulnerabilities Translated from German

  CVE-2026-106435CVE-2026-106434CVE-2026-106429+10 more CVEs

[ References ]References

• jira.mongodb.org/browse/MONGOCRYPT-986