Vulnerability in MongoDB C Driver

[ Description ]Official description

The BSON buffer-reservation API in the MongoDB C Driver can record a length smaller than the five-byte BSON minimum. Later append or comparison operations can underflow unsigned length calculations and read or write outside the document buffer. An actor who can influence the length supplied by an embedding application can cause the application to terminate or read or corrupt adjacent process memory. Reaching this issue requires the application to pass an undersized value to bson_reserve_buffer and then perform an affected operation.

[ 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/CDRIVER-6423