OpenVPN up to 2.0.0 denial of service

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

A vulnerability was found in OpenVPN up to 2.0.0 (Network Encryption Software). It has been declared as problematic. Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

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.

The bug was discovered 08/19/2005. The weakness was presented 08/24/2005 (Website). It is possible to read the advisory at mandriva.com. This vulnerability is known as CVE-2005-2531 since 08/10/2005. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 21488 (FreeBSD : openvpn -- denial of service: client certificate validation can disconnect unrelated clients (a51ad838-2077-48b2-a136-e888a7db5f8d)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family FreeBSD Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 38467 (OpenVPN Failed Authentication Denial of Service Vulnerability).

Upgrading to version 2.0.1 eliminates this vulnerability. A possible mitigation has been published even before and not after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at X-Force (21923) and Tenable (21488). See 26772, 26743, 26146 and 26145 for similar entries.

Productinfo

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Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
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CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔍
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Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 21488
Nessus Name: FreeBSD : openvpn -- denial of service: client certificate validation can disconnect unrelated clients (a51ad838-2077-48b2-a136-e888a7db5f8d)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍
Nessus Port: 🔍

OpenVAS ID: 55602
OpenVAS Name: Debian Security Advisory DSA 851-1 (openvpn)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
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Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: OpenVPN 2.0.1

Timelineinfo

08/10/2005 🔍
08/19/2005 +9 days 🔍
08/19/2005 +0 days 🔍
08/19/2005 +0 days 🔍
08/19/2005 +0 days 🔍
08/24/2005 +5 days 🔍
08/24/2005 +0 days 🔍
11/15/2005 +83 days 🔍
05/13/2006 +179 days 🔍
03/11/2015 +3224 days 🔍
06/11/2019 +1553 days 🔍

Sourcesinfo

Advisory: mandriva.com
Status: Not defined
Confirmation: 🔍

CVE: CVE-2005-2531 (🔍)
X-Force: 21923
Vulnerability Center: 9632 - OpenVPN Remote DoS via Large Number of Failed Authentication Attempts, Low
SecurityFocus: 14605 - OpenVPN Failed Authentication Denial Of Service Vulnerability
Secunia: 16463 - OpenVPN Multiple DoS Vulnerabilities, Moderately Critical
OSVDB: 18882 - OpenVPN - Failed Authentication Denial Of Service Issue

See also: 🔍

Entryinfo

Created: 03/11/2015 23:39
Updated: 06/11/2019 12:27
Changes: 03/11/2015 23:39 (74), 06/11/2019 12:27 (7)
Complete: 🔍

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