---
id: CVE-2026-96748
title: >-
  PyMongo's connection string parsing decodes percent-encoded characters in the
  host portion before the host list is separated on its delimiters
summary: >-
  PyMongo's connection string parsing decodes percent-encoded characters in the
  host portion before the host list is separated on its delimiters. When an
  application places a hostname value supplied by an unauthenticated party into
  a conne…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'
cwe:
  - CWE-177
  - CWE-140
vendor: MongoDB
product: Python Driver
affected:
  - python_driver < 4.18.2
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:00:46.893'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96748'
references:
  - url: >-
      https://github.com/mongodb/mongo-python-driver/blob/4.18.2/doc/changelog.rst
    label: cna@mongodb.com
  - url: 'https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.2'
    label: cna@mongodb.com
  - url: >-
      https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-vp6j-j7w5-5xjj
    label: cna@mongodb.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96748.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-96748'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2540685'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-96748'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96748'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-24T18:36:30.450714Z'
ingestedAt: '2026-09-24T18:49:36.719Z'
---

## Overview

PyMongo's connection string parsing decodes percent-encoded characters in the host portion before the host list is separated on its delimiters. When an application places a hostname value supplied by an unauthenticated party into a connection string, that party may cause additional servers of their choosing to be added to the application's database client. The application may then send its authentication exchange and database operations to one of those servers, which can observe limited information and return altered results.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat OpenShift AI (RHOAI), Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1 · no fix planned: Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1, Red Hat OpenShift AI (RHOAI) · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96748.json)