Improper validation of certificate with host mismatch in Apache HttpComponents Client - CVE-2026-71290
Published: August 24, 2026
Vulnerability identifier: #VU144886
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-71290
CWE-ID: CWE-297
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to impersonate the server.
The vulnerability exists due to improper certificate validation in the async transport of HttpClient when establishing TLS connections with HostnameVerificationPolicy#BUILTIN. A remote attacker can intercept and modify traffic and present a valid certificate for a different domain to impersonate the server.
The classic version of HttpClient is not affected.
Affected software
Apache HttpComponents Client
How to mitigate CVE-2026-71290
Install security update from vendor's website.
Apache HttpComponents Client - update to 5.6.4