Race Condition Affecting openvpn package, versions <2.4.9-r0


Severity

Recommended
0.0
low
0
10

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Threat Intelligence

EPSS
0.34% (72nd percentile)

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  • Snyk IDSNYK-ALPINE311-OPENVPN-1279497
  • published21 Jul 2020
  • disclosed27 Apr 2020

Introduced: 27 Apr 2020

CVE-2020-11810  (opens in a new tab)
CWE-362  (opens in a new tab)

How to fix?

Upgrade Alpine:3.11 openvpn to version 2.4.9-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream openvpn package and not the openvpn package as distributed by Alpine. See How to fix? for Alpine:3.11 relevant fixed versions and status.

An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

CVSS Scores

version 3.1