Review reviewHigh

CVE-2026-40542

Apache Software Foundation Apache HttpClient, Cryostat 4, Migration Toolkit for Applications 8

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
7.3
EPSS
0.46%
37.3% percentile
CISA KEV
Not listed
Published
2026.04.22
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.46%
Technical severityCVSS 7.3

Vulnerability overview

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.

Affected product and versions

Product
Apache Software Foundation Apache HttpClient, Cryostat 4, Migration Toolkit for Applications 8
Affected versions
>= 5.6 < 5.6.1, 5.6
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Apache Software Foundation Apache HttpClient, Cryostat 4, Migration Toolkit for Applications 8 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CWE
CWE-304, CWE-325