CVE-2026-96747.

Disclosure summary

### Summary PyMongo passed the KMS endpoint of a data key verbatim into `parse_host()`, which returns any string ending in `.sock` unchanged instead of validating it as a hostname and port. The driver's connection code then treats such an address as a Unix domain socket path and connects to it with `AF_UNIX`. Because the endpoint originates from `masterKey.endpoint` in a key vault document, a party who can write to the key vault could redirect the driver's KMS connection to an arbitrary Unix domain socket path on the application host. ### Impact An application using client-side field level encryption (CSFLE) or Queryable Encryption is affected if an attacker can write to its key vault collection. Setting `masterKey.endpoint` on a data key to a `.sock`-suffixed string causes the next KMS request for that key (key cache TTL is ~60 seconds) to open an `AF_UNIX` connection to the attacker-chosen filesystem path from inside the victim application process. The documented custom KMS endpoint feature supports TCP hosts only, so this crosses a boundary the feature was never intended to allow. Impact is limited to the side effects of the connection itself. The socket is still wrapped in a ve

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Original records & references

• NIST NVD record
• CVE Program record
• github.com — Reviewed advisory

PUBLISHED 2026-10-05T19:46:53-04:00
MODIFIED 2026-10-05T19:46:54-04:00
INGESTED 2026-10-06T11:45:42-04:00