The MongoDB Python Driver's binary accelerator can read outside a buffer when an application decodes malformed BSON containing a truncated regular-expression element without a trailing NUL byte. An actor who can supply BSON to the documented decode or decodeall API can cause the application process to terminate when the C extension is loaded. The driver's normal database wire-protocol path does not reach this code.

Impact

When reading/writing via an ID with the GridFS API, require an exact match on the given ID. Otherwise, if a Hash is given in place of the ID, it may be interpreted as criteria, overriding the ID match.

Patches Patch available in pymongo >= 4.18.1

Workarounds Ensure your existing workflow only supports exact matching on the GridFS API.