MitM attack in Logstash

1) Improper certificate validation

EUVDB-ID: #VU108738

Risk: Medium

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

CVE-ID: CVE-2025-37730

CWE-ID: CWE-295 - Improper Certificate Validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to missing certificate validation in TCP output in the client mode when "ssl_verification_mode = full" is set. A remote attacker with ability to intercept traffic can perform MitM attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Logstash: 8.0.0 - 9.0.0

CPE2.3

• cpe:2.3:a:elastic_stack:logstash:8.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.1.2:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.1.3:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.2.2:*:*:*:*:*:*:*
• cpe:2.3:a:elastic_stack:logstash:8.2.3:*:*:*:*:*:*:*

External links

https://discuss.elastic.co/t/logstash-8-17-6-8-18-1-and-9-0-1-security-update-esa-2025-08/377869

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

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