What is CVE-2026-40542?

CVE-2026-40542 is a high-severity vulnerability in Apache Httpclient, classified under Missing Critical Step in Authentication. CVSS score: 7.3/10. Published 2026-04-22.

How severe is CVE-2026-40542?

High severity. CVSS v3 base score is 7.3 out of 10.

Vulnerability in Apache Httpclient

CVE-2026-40542

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…

EPSS: 0.001 (17.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.

Affected products

Apache Httpclient — versions 5.6
Apache Software Foundation Httpclient — versions 5.6

Weakness classification (CWE)

CWE-304 — Missing Critical Step in Authentication

References

security@apache.org (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-40542?: CVE-2026-40542 is a high-severity vulnerability in Apache Httpclient, classified under Missing Critical Step in Authentication. CVSS score: 7.3/10. Published 2026-04-22.
How severe is CVE-2026-40542?: High severity. CVSS v3 base score is 7.3 out of 10.