#VU51713 Improper Certificate Validation in Logstash - CVE-2021-22138

Vulnerability identifier: #VU51713

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-22138

CWE-ID: CWE-295

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Logstash
Server applications / Other server solutions

Vendor: Elastic Stack

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to improper TLS certificate validation in the monitoring feature of Logstash. When specifying a trusted server CA certificate Logstash does not properly verify the certificate returned by the monitoring server. A remote attacker can preform a Man-in-the-Middle attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Logstash: 6.4.0 - 6.4.3, 6.5.0 - 6.5.4, 6.6.0 - 6.6.2, 6.7.0 - 6.7.2, 6.8.0 - 6.8.14, 7.0.0 - 7.0.1, 7.1.0 - 7.11.2, 7.2.0 - 7.2.1, 7.3.0 - 7.3.2, 7.4.0 - 7.4.2, 7.5.0 - 7.5.2, 7.6.0 - 7.6.2, 7.7.0 - 7.7.1, 7.8.0 - 7.8.1, 7.9.0 - 7.9.3

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External links
https://www.elastic.co/community/security#ESA-2021-09

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.