Disclosure summary
An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party with no privileges who can place a very large value into data that an application encodes may, depending on how the native extension was built, cause a write outside the bounds of an allocated buffer inside the application's own process.
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.
GitHub Reviewed Security Advisories · GHSA-v4x9-3549-crwv
Open original source · Updated Oct 05, 2026
PyMongo: PYTHON-5996 Heap out-of-bounds write via signed size overflow in BSON document encoding
Source severity: HIGH / 7.5
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| pip | pymongo | < 4.18.2 | 4.18.2 |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Reviewed advisory
PUBLISHED 2026-10-05T19:47:10-04:00
MODIFIED 2026-10-05T19:47:11-04:00
INGESTED 2026-10-06T11:45:42-04:00