CVE-2026-64607: Apache Httpclient

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

HttpClient based on the classic i/o model fails to correctly release the underlying connection back to the connection manager if it encounters an invalid or unsupported `Content-Encoding` header value in the response message. Please note this defect does not affect HttpClient based on the async i/o model. This issue affects Apache HttpComponents Client: from 5.0-alpha1 through 5.6.2.

Affected products

• Apache Httpclient: from 5.0.0, before 5.6.3 (fixed in 5.6.3)

Published 2026-07-31. Last modified 2026-08-13.