CVE-2026-45389
Received Received - Intake
OCaml-TLS Client Authentication Certificate Impersonation

Publication date: 2026-06-15

Last updated on: 2026-06-15

Assigner: MITRE

Description
In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client (when doing client authentication), which allows impersonation with certificates that are not meant for client authentication (because of KeyUsage and ExtendedKeyUsage).
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Meta Information
Published
2026-06-15
Last Modified
2026-06-15
Generated
2026-06-16
AI Q&A
2026-06-15
EPSS Evaluated
N/A
NVD
CVE-2026-45389
EUVD
EUVD-2026-36765
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
ocaml_tls ocaml_tls to 2.1.0 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in OCaml-TLS versions before 2.1.0. The server implementation does not properly verify the certificate provided by the client during client authentication. Specifically, it fails to check whether the certificate is intended for client authentication based on its KeyUsage and ExtendedKeyUsage fields.

Impact Analysis

Because the server does insufficient checks on client certificates, an attacker could impersonate a client using a certificate that is not meant for client authentication. This could lead to unauthorized access or impersonation in systems relying on OCaml-TLS for secure client authentication.

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