Connection redirection via encoded host delimiter injection
Published Sep 24, 2026 · Updated Sep 24, 2026
Connection-string injection in MongoDB PyMongo before 4.18.2 allows remote attackers to redirect database connections to chosen servers. The host parser percent-decodes hostname text before splitting the host list, so an encoded delimiter becomes an additional server entry. Exploitation requires an application to place an unauthenticated party's hostname value into the URI; the added server can observe authentication exchanges and return altered database results.
Summary
What happened
Connection-string injection in MongoDB PyMongo before 4.18.2 allows remote attackers to redirect database connections to chosen servers. The host parser percent-decodes hostname text before splitting the host list, so an encoded delimiter becomes an additional server entry. Exploitation requires an application to place an unauthenticated party's hostname value into the URI; the added server can observe authentication exchanges and return altered database results.
The record
- CVE
- CVE-2026-96748
- Published
- Sep 24, 2026
- Updated
- Sep 24, 2026
- Vendor
- MongoDB
- Product
- PyMongo
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 24, 2026CVE publishedPublication date reported by the CVE source.
- Sep 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <4.18.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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