Description
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.
Published: 2026-09-24
Score: 8.3 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Thu, 24 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 24 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Connection redirection via percent-encoded delimiter injection in connection string hosts
Weaknesses CWE-177
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'}

cvssV4_0

{'score': 8.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: mongodb

Published:

Updated: 2026-09-24T19:12:05.362Z

Reserved: 2026-09-23T15:45:50.867Z

Link: CVE-2026-96748

cve-icon Vulnrichment

Updated: 2026-09-24T18:36:33.745Z

cve-icon NVD

Status : Received

Published: 2026-09-24T19:17:20.813

Modified: 2026-09-24T19:17:20.813

Link: CVE-2026-96748

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-177

    Improper Handling of URL Encoding (Hex Encoding)