How severe is CVE-2026-40542?

CVE-2026-40542 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-40542 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40542?

CVE-2026-40542 affects Apache Httpclient. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40542?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40542 have an EU (EUVD) identifier?

Yes. CVE-2026-40542 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24630.

When was CVE-2026-40542 published?

CVE-2026-40542 was published on 2026-04-22 and last updated on 2026-09-09.

CVE-2026-40542

CVE-2026-40542 is a high-severity vulnerability in Apache Httpclient with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-304.

Key facts

Severity: High (CVSS 3.x base score 7.3)
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-24630
Weakness: CWE-304
Affected product: Apache Httpclient
Published: 2026-04-22
Last modified: 2026-09-09

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.

Frequently asked questions

What is 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 5.6.1, which fixes this issue.
How severe is CVE-2026-40542?: CVE-2026-40542 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-40542 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40542?: CVE-2026-40542 affects Apache Httpclient. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40542?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40542 have an EU (EUVD) identifier?: Yes. CVE-2026-40542 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24630.
When was CVE-2026-40542 published?: CVE-2026-40542 was published on 2026-04-22 and last updated on 2026-09-09.

References

Affected products (1)

cpe:2.3:a:apache:httpclient:5.6:-:*:*:*:*:*:*

More vulnerabilities in Apache Httpclient

CVE-2013-4366 — Critical (CVSS 9.8): http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that…
CVE-2026-71290 — Critical (CVSS 9.1): Improper TLS hostname verification vulnerability in Apache HttpComponents Client 5.4 or…
CVE-2025-27820 — High (CVSS 7.5): A bug in PSL validation logic in Apache HttpClient 5.4.x disables domain checks, affecting cookie management and host…
CVE-2014-3577 — Medium (CVSS 5.8): org.apache.http.conn.ssl.AbstractVerifier in Apache HttpComponents HttpClient before 4.3.5 and HttpAsyncClient before…
CVE-2012-5783 — Medium (CVSS 5.8): Apache Commons HttpClient 3.x, as used in Amazon Flexible Payments Service (FPS) merchant Java SDK and other products,…
CVE-2026-64607 — Medium (CVSS 5.3): HttpClient based on the classic i/o model fails to correctly release the underlying connection back to the connection…

All CVEs affecting Apache Httpclient →

Other CWE-304 vulnerabilities

CVE-2023-54391 — Critical (CVSS 9.8): Proxmox Virtual Environment (VE) 7.0 through 8.0 contains an authentication bypass vulnerability in…
CVE-2024-8954 — Critical (CVSS 9.8): In composiohq/composio version 0.5.10, the API does not validate the `x-api-key` header's value during the…
CVE-2024-2172 — Critical (CVSS 9.8): The Malware Scanner plugin and the Web Application Firewall plugin for WordPress (both by MiniOrange) are vulnerable to…
CVE-2026-94052 — Critical (CVSS 9.1): A missing check in LdapPasswordAuthenticator in component sshd-ldap in Apache MINA SSHD versions 1.2.0 to 2.19.0 or…
CVE-2026-59564 — Critical (CVSS 9.1): An authentication bypass issue exists in communications between affected versions of the Zscaler Client Connector and…
CVE-2026-61466 — Critical (CVSS 9.1): In Apache CXF's OAuth2 Dynamic Client Registration endpoint, the authorization server accepts and stores the `scope`…

Browse all CWE-304 vulnerabilities →