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.
https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-v4x9-3549-crwv
https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.2
https://github.com/mongodb/mongo-python-driver/blob/4.18.2/doc/changelog.rst
Published: 2026-09-24
Updated: 2026-09-24
Base Score: 7.2
Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C
Severity: High
Base Score: 8.4
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: High
Base Score: 7.5
Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High