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TITLE:
OpenVPN Multiple DoS Vulnerabilities

SECUNIA ADVISORY ID:
SA16463

VERIFY ADVISORY:
http://secunia.com/advisories/16463/

CRITICAL:
Moderately critical

IMPACT:
DoS

WHERE:
>From remote

SOFTWARE:
OpenVPN 1.x
http://secunia.com/product/3952/
OpenVPN 2.x
http://secunia.com/product/5568/

DESCRIPTION:
Some vulnerabilities have been reported in OpenVPN, which can be
exploited by malicious people and users to cause a DoS (Denial of
Service).

1) An error in flushing the OpenSSL error queue due to a failed
client certificate authentication can be exploited to cause another
unrelated client to be disconnected.

Successful exploitation requires OpenVPN to run with "verb 0" and
without "tls-auth".

2) An error in flushing the OpenSSL error queue when the server fails
to decrypt a received packet can be exploited by an authenticated
client to disconnect another client via a malformed packet

3) An authenticated client configured in "dev tap" ethernet bridging
mode can flood the server with many packets, each with a different
spoofed MAC address, and cause the server to deplete system memory.

4) Two or more clients connecting to the server at the same time
using the same client certificate can cause a race condition that
will crash the server.

Successful exploitation requires that the "duplicate-cn" option is
not enabled on the server.

SOLUTION:
Update to version 2.0.1.
http://openvpn.net/download.html

PROVIDED AND/OR DISCOVERED BY:
Reported by vendor.

ORIGINAL ADVISORY:
http://openvpn.net/changelog.html

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About:
This Advisory was delivered by Secunia as a free service to help
everybody keeping their systems up to date against the latest
vulnerabilities.

Subscribe:
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Definitions: (Criticality, Where etc.)
http://secunia.com/about_secunia_advisories/


Please Note:
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