CVE-2026-96748

Connection redirection via percent-encoded delimiter injection in connection string hosts

Published Sep 24, 2026 CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-vp6j-j7w5-5xjj PyMongo: PYTHON-5986 Host injection in PyMongo connection string parsing via percent-encoded delimiters
History
Type Values Removed Values Added
First Time appeared Mongodb
Mongodb python Driver
Vendors & Products Mongodb
Mongodb python Driver
Type Values Removed Values Added
References
Metrics ssvc

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

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mongodb
Published
Updated
Sep 24, 2026, 7:12 PM
Reserved
Sep 23, 2026, 3:45 PM
Status
Awaiting Analysis
Published
Sep 24, 2026, 7:17 PM
Modified
Sep 24, 2026, 9:00 PM
Severity
Moderate
Public date
Sep 24, 2026, 6:18 PM