Improper validation of certificate with host mismatch in SKS Keyserver and GnuPG

#VU20961 Improper validation of certificate with host mismatch in SKS Keyserver and GnuPG

Published: 2019-09-10

Vulnerability identifier: #VU20961

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-13050

CWE-ID: CWE-297

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
SKS Keyserver
Server applications / Other server solutions
GnuPG
Client/Desktop applications / Encryption software

Vendor: sks-keyservers.net
GNU

Description

The vulnerability allows a remote attacker to cause a persistent denial of service (DoS) condition on the target system.

The vulnerability exists due to the interaction between the vulnerable applications makes it risky to have a GnuPG keyserver configuration line referring to a host on the SKS keyserver network. A remote attacker can retrieve data from this network and cause a persistent denial of service, because of a certificate spamming attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

SKS Keyserver: 1.2.0

GnuPG: 1.0.0 - 2.2.16

External links
http://gist.github.com/rjhansen/67ab921ffb4084c865b3618d6955275f
http://lists.gnupg.org/pipermail/gnupg-announce/2019q3/000439.html