CVE-2026-40542 Apache Software Foundation CVE debrief

Who should care

Organizations using Apache HttpClient 5.6 should prioritize upgrading to version 5.6.1 to mitigate this vulnerability. This vulnerability could allow an attacker to bypass authentication, potentially leading to unauthorized access or data breaches. Security teams and developers responsible for maintaining and updating software dependencies should be aware of this issue and take necessary actions.

Technical summary

The vulnerability in Apache HttpClient 5.6 is due to a missing critical step in authentication, specifically for SCRAM-SHA-256 authentication. This allows an attacker to cause the client to accept this authentication method without proper mutual authentication verification. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L, indicating a high severity. The CWE for this vulnerability is CWE-304, related to Missing Critical Step in Authentication. Red Hat has also provided additional information and potential mitigations for this vulnerability.

Defensive priority

High priority should be given to upgrading Apache HttpClient to version 5.6.1. Security teams should also review and update their inventory of affected systems and monitor for potential exploitation attempts.

Recommended defensive actions

• Upgrade Apache HttpClient to version 5.6.1
• Review and update inventory of affected systems
• Monitor for potential exploitation attempts
• Implement additional authentication verification for SCRAM-SHA-256
• Consider compensating controls for authentication

Evidence notes

The CVE record and NVD detail provide official information about the vulnerability. The source item URL provides additional metadata and references related to the vulnerability. Apache and Red Hat have provided information and potential mitigations for this vulnerability.

Official resources