CVE-2026-40542

Modified Modified - Updated After Analysis

Authentication Bypass in Apache HttpClient 5.6 via SCRAM-SHA

Publication date: 2026-04-22

Last updated on: 2026-06-30

Assigner: Apache Software Foundation

Description

Missing critical step in authentication in Apache HttpClient 5.6 allows an attacker to cause the client to accept SCRAM-SHA-256 authentication without proper mutual authentication verification. Users are recommended to upgrade to version 5.6.1, which fixes this issue.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-04-22

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-04-22

EPSS Evaluated

2026-07-05

NVD

CVE-2026-40542

EUVD

EUVD-2026-24630

Affected Vendors & Products

Vendor	Product	Version / Range
apache	httpclient	5.6

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-304	The product implements an authentication technique, but it skips a step that weakens the technique.
CWE-325	The product does not implement a required step in a cryptographic algorithm, resulting in weaker encryption than advertised by the algorithm.

Attack-Flow Graph

Executive Summary

This vulnerability is a missing critical step in the authentication process in Apache HttpClient version 5.6. It allows an attacker to cause the client to accept SCRAM-SHA-256 authentication without proper mutual authentication verification.

This means that the client may trust an authentication attempt that has not been fully verified, potentially allowing unauthorized access.

Users are recommended to upgrade to version 5.6.1, which fixes this issue.

Compliance Impact

The provided information does not specify how the vulnerability in Apache HttpClient 5.6 impacts compliance with common standards and regulations such as GDPR or HIPAA.

Impact Analysis

This vulnerability can impact you by allowing an attacker to bypass proper mutual authentication verification when using Apache HttpClient 5.6 with SCRAM-SHA-256 authentication.

As a result, an attacker could potentially impersonate a legitimate server or client, leading to unauthorized access or data interception.

Mitigation Strategies

Users are recommended to upgrade Apache HttpClient to version 5.6.1, which fixes the authentication issue allowing acceptance of SCRAM-SHA-256 without proper mutual authentication verification.

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