How severe is CVE-2026-45389?

CVE-2026-45389 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-45389 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-45389?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45389 have an EU (EUVD) identifier?

Yes. CVE-2026-45389 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36765.

When was CVE-2026-45389 published?

CVE-2026-45389 was published on 2026-06-15 and last updated on 2026-06-17.

CVE-2026-45389

CVE-2026-45389 is a high-severity vulnerability with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: High (CVSS 3.x base score 7.4)
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-36765
Weakness: CWE-295
Published: 2026-06-15
Last modified: 2026-06-17

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).

Frequently asked questions

What is CVE-2026-45389?: 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).
How severe is CVE-2026-45389?: CVE-2026-45389 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-45389 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-45389?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45389 have an EU (EUVD) identifier?: Yes. CVE-2026-45389 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36765.
When was CVE-2026-45389 published?: CVE-2026-45389 was published on 2026-06-15 and last updated on 2026-06-17.

References

https://osv.dev/vulnerability/OSEC-2026-07

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