CVE-2026-71290: Apache HttpComponents Client: TLS hostname verification silently disabled on the async transport (default config, MITM)

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-11 · updated 2026-10-24
Weakness: CWE-295

Description

Improper TLS hostname verification vulnerability in Apache HttpComponents Client 5.4 or newer. HostnameVerificationPolicy#BUILTIN setting has no effect when used with the async version of HttpClient. An attacker that can intercept and modify traffic between the client and the server can impersonate the server by presenting a valid certificate for a different domain. Please note the classic version of HttpClient is not affected by this vulnerability. Affected users are recommended to upgrade to at least version 5.6.4, which fixes the issue.

Affected products

Apache Software Foundation Apache HttpClient: from 5.4 before 5.6.4 — fixed in 5.6.4

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache HttpClient 5.6.4. Check the vendor advisory for mitigations.

References

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