CVE-2026-45388 Details
Description
In OCaml-TLS before 2.1.0, the client implementation does insufficient checks of the certificate provided by the server, which allows impersonation with certificates that are not meant for server authentication (because of KeyUsage and ExtendedKeyUsage).
A vulnerability exists in the OCaml-TLS library, specifically in versions prior to 2.1.0, within the TLS 1.3 client implementation. The issue arises from inadequate validation of server certificates, allowing impersonation using certificates not intended for server authentication. This flaw exploits the KeyUsage and ExtendedKeyUsage extensions, which are crucial for determining the appropriate use of a certificate. The vulnerability can be exploited by presenting a certificate issued for client authentication or other non-server purposes, thereby misleading the OCaml-TLS client into accepting it as a valid server certificate.
Users can upgrade to OCaml-TLS version 2.1.0 or later, where this vulnerability has been addressed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jun 15, 2026CISA-ADP
Assessed Jun 16, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://osv.dev/vulnerability/OSEC-2026-06 | CISA-ADP | AdvisoryRemedy |
| https://osv.dev/vulnerability/OSEC-2026-06 | [email protected] | AdvisoryRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-295 | Improper Certificate Validation | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| OCaml-TLS | < 2.1.0 (semver) |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 16, 2026 | CVE Modified | CISA-ADP |
| Jun 15, 2026 | New CVE Received | [email protected] |