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Vulnerability record · CVE-2026-96748 · published 24 September 2026

CVE-2026-96748: PyMongo's connection string parsing decodes percent-encoded characters in the host portion before the host lis…

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.

8.3 CVSS 4.0 High EPSS 0.26% · top 84.4% CWE-177 · CWE-177 Awaiting Analysis
8.3CVSS 4.0 base score
0.26%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
24 Sep 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

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Source: NIST National Vulnerability Database (record CVE-2026-96748), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.