Vulnerability GHSA-v4x9-3549-crwv

High Risk
HIGH RISK
CVSS Score: 8.4
Score Range: 7.0–8.9
High severity vulnerabilities (CVSS 7.0–8.9). Serious vulnerabilities that should be prioritized soon after critical fixes.
7 hours ago
October 05, 2026 at 11:47 PM UTC
PyMongo: PYTHON-5996 Heap out-of-bounds write via signed size overflow in BSON document encoding
0.1pre - 4.18.1
0.1pre - 4.18.1

Summary

PyMongo: PYTHON-5996 Heap out-of-bounds write via signed size overflow in BSON document encoding

Details

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.

Impacted packages

Timeline

Published
7 hours ago
October 05, 2026 at 11:47 PM UTC
Fixed (4.18.2)
11 days ago
September 24, 2026 at 04:58 PM UTC
Last Modified
7 hours ago
October 06, 2026 at 12:00 AM UTC