# CVE-2026-96748: Connection redirection via percent-encoded delimiter injection in connection string hosts

> CVE-2026-96748: Connection redirection via percent-encoded delimiter injection in connection string hosts. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-96748
Last updated: 2026-09-24T21:00:46Z

- Published: 2026-09-24 18:18 UTC · Updated: 2026-09-24 21:00 UTC · Assigner: mongodb
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
- EPSS: 0.36%, 30th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-177

## 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.

## Affected vendors and products

- MongoDB: Python Driver

## Tracked companies

- [MongoDB Atlas](https://rewindex.com/company/mongodb-atlas.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-96748)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-96748)
- [https://github.com/mongodb/mongo-python-driver/blob/4.18.2/doc/changelog.rst](https://github.com/mongodb/mongo-python-driver/blob/4.18.2/doc/changelog.rst)
- [https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.2](https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.2)
- [https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-vp6j-j7w5-5xjj](https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-vp6j-j7w5-5xjj)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-96748 · Markdown: https://rewindex.com/cve/CVE-2026-96748.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-96748 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:15:23.066Z