Vulnerability in MongoDB libmongocrypt

[ Description ]Official description

Improper state management in MongoDB libmongocrypt can cause provider-specific data to be treated as an incompatible type when cleaning up a key document containing duplicate masterKey fields. An authenticated actor who can modify key vault documents, or a server that returns such a key document, can cause invalid memory access and invalid frees in the client process. This can terminate the application or corrupt process memory.

[ 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-964