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Vulnerability · Published Apr 22, 2026 · Assigned by apache

CVE-2026-40542Apache HttpClient: SCRAM-SHA-256 mutual authentication bypass may cause the client to accept authentication without proper mutual authentication verification

High 7.3

In plain English

A high-severity security flaw in Apache HttpClient from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)0.5%top 54.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Mavenorg.apache.httpcomponents.client5:httpclient55.6.1GHSA-v468-qcjx-r72w
Ubuntu:22.04:LTShttpcomponents-clientno fix listedUBUNTU-CVE-2026-40542
Ubuntu:24.04:LTShttpcomponents-clientno fix listedUBUNTU-CVE-2026-40542
Ubuntu:25.10httpcomponents-clientno fix listedUBUNTU-CVE-2026-40542
Ubuntu:26.04:LTShttpcomponents-clientno fix listedUBUNTU-CVE-2026-40542
Ubuntu:26.10httpcomponents-clientno fix listedUBUNTU-CVE-2026-40542

Affected products (as reported)

VendorProductVersions
Apache Software Foundation Apache HttpClient 5.6 – before 5.6.1

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

References