---
id: CVE-2026-106435
title: >-
  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
summary: >-
  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 docume…
severity: medium
cvss: 5.1
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
vendor: mongodb
product: python_driver
affected:
  - python_driver < 4.18.3
patched:
  - python_driver 4.18.3
published: '2026-10-08'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T17:00:36.980'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-106435'
references:
  - url: 'https://jira.mongodb.org/browse/PYTHON-6110'
    label: cna@mongodb.com
  - url: >-
      https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-98qm-wvgf-w4cf
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-106435'
  - url: 'https://github.com/mongodb/mongo-python-driver/pull/3109'
  - url: >-
      https://github.com/mongodb/mongo-python-driver/commit/bb8d4e195275e75bd94ebeffb53cc747d357fcf4
  - url: 'https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.3'
  - url: 'https://github.com/advisories/GHSA-98qm-wvgf-w4cf'
  - url: 'https://github.com/mongodb/mongo-python-driver'
tags:
  - nvd
  - cve.org
  - ghsa
  - pip
  - osv
epss: 0.00093
epssPercentile: 0.00562
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-09T11:49:15.521416Z'
ingestedAt: '2026-10-08T22:11:53.856Z'
aliases:
  - GHSA-98qm-wvgf-w4cf
ecosystem: pip
---

## Overview

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 decode_all 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.

## Affected

- `python_driver < 4.18.3`

## Remediation

Upgrade past the affected range:

- `python_driver 4.18.3`

## Package advisory (CVE-2026-106435)

Affected packages:

- `pymongo >= 3.9.0, <= 4.18.2`

Patched in:

- `pymongo 4.18.3`

Source: https://github.com/advisories/GHSA-98qm-wvgf-w4cf