CVE-2025-37730Network attack vector

Traffic interception via omitted TLS hostname verification

Published May 6, 2025 · Updated May 6, 2025

Improper certificate validation in Elastic Logstash before 8.17.6, 8.18.0, and 9.0.0 allows remote attackers to intercept TCP output traffic. In client mode, the TCP output plugin completes TLS without calling SSLSocket.post_connection_check for the configured host even when ssl_verification_mode is full. An attacker positioned between Logstash and its TCP destination can read or alter transmitted data; the affected full-verification setting is the default.

CVSS severity5.9
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper certificate validation in Elastic Logstash before 8.17.6, 8.18.0, and 9.0.0 allows remote attackers to intercept TCP output traffic. In client mode, the TCP output plugin completes TLS without calling SSLSocket.post_connection_check for the configured host even when ssl_verification_mode is full. An attacker positioned between Logstash and its TCP destination can read or alter transmitted data; the affected full-verification setting is the default.

The record

CVE
CVE-2025-37730
Published
May 6, 2025
Updated
May 6, 2025
Vendor
Elastic
Product
Logstash
Classifications
CWE-295, CAPEC-475, CAPEC-459, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2025CVE publishedPublication date reported by the CVE source.
  2. May 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=8.0.0 <8.17.6
  2. Affected versionversion=8.18.0 <8.18.1
  3. Affected versionversion=9.0.0 <9.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Elastic · Logstashversion=8.0.0 <8.17.6; version=8.18.0 <8.18.1; version=9.0.0 <9.0.1

Published CVSS scores

5.9ElasticCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
CAPEC-475Signature Spoofing by Improper Validation
CAPEC-459Creating a Rogue Certification Authority Certificate
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo