CVE-2005-2531

CVE-2005-2531 is a medium-severity vulnerability in Openvpn with a CVSS 2.0 base score of 5.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

OpenVPN before 2.0.1, when running with "verb 0" and without TLS authentication, does not properly flush the OpenSSL error queue when a client fails certificate authentication to the server and causes the error to be processed by the wrong client, which allows remote attackers to cause a denial of service (client disconnection) via a large number of failed authentication attempts.

Frequently asked questions

What is CVE-2005-2531?
OpenVPN before 2.0.1, when running with "verb 0" and without TLS authentication, does not properly flush the OpenSSL error queue when a client fails certificate authentication to the server and causes the error to be processed by the wrong client, which allows remote attackers to cause a denial of service (client disconnection) via a large number of failed authentication attempts.
How severe is CVE-2005-2531?
CVE-2005-2531 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2005-2531 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2005-2531?
CVE-2005-2531 primarily affects Openvpn. In total, 74 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2005-2531?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2005-2531 published?
CVE-2005-2531 was published on 2005-08-24 and last updated on 2026-06-16.

References

Affected products (74)

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