Security Bulletin
Summary
Apache HttpComponents Client is affected by two vulnerabilities (CVSS up to 9.1, Critical). CVE-2026-71290 (CVSS 9.1) is an improper TLS hostname verification flaw in the async HttpClient (versions 5.4 and later) where HostnameVerificationPolicy#BUILTIN has no effect, allowing a network attacker to intercept traffic and impersonate the server using a valid certificate for a different domain. CVE-2026-64607 (CVSS 5.3) is a connection leak in the classic (synchronous) HttpClient (versions 5.0-alpha1 through 5.6.2) where an invalid or unsupported Content-Encoding response header prevents the connection from being properly returned to the connection manager, leading to resource exhaustion. Upgrade to Apache HttpComponents Client 5.6.4 or later to remediate both issues.
Vulnerability Details
CVEID: CVE-2026-64607
DESCRIPTION: 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.
CWE: CWE-772: Missing Release of Resource after Effective Lifetime
CVSS Source: CISA ADP
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
CVEID: CVE-2026-71290
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.
CWE: CWE-295: Improper Certificate Validation
CVSS Source: CISA ADP
CVSS Base score: 9.1
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| IBM Content Navigator | 26.0.0.0 |
| IBM Content Navigator | 3.1.0.0 |
| IBM Content Navigator | 3.2.0.0 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now by upgrading.
| Affected Product(s) | Version(s) | Remediation / Fix |
| IBM Content Navigator | 26.0.0.0 | Apply security fix 26.0.0-IF003 |
| IBM Content Navigator | 3.1.0.0 | Apply security fix 3.1.0-IF013 |
| IBM Content Navigator | 3.2.0.0 | Apply security fix 3.2.0-IF008 |
Workarounds and Mitigations
None
Get Notified about Future Security Bulletins
References
Release Notes:
https://www.ibm.com/support/pages/ibm-content-navigator-version-2600-interim-fix-3-readme
https://www.ibm.com/support/pages/ibm-content-navigator-version-320-interim-fix-8-readme
https://www.ibm.com/support/pages/ibm-content-navigator-version-310-interim-fix-13-readme
Acknowledgement
Change History
28 Sep 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
28 September 2026
Initial Publish date:
28 September 2026
UID
ibm17289746