CVE-2026-40542

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

HIGH
7.3
CVSS Score
Published: April 22, 2026 at 07:07 AM UTC
Updated: September 9, 2026 at 01:19 PM UTC
2 products affected across 2 vendorsHttpclientOpenShift Developer Tools and Services

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Severity
HIGH7.3
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.6 ≤ v < 5.6.15.6
Affected range stops below 5.6.1, so it looks safe — our inference, not a vendor statement
All versions
Vendor states this is fixed in 1786533561 (unaffected)
Vendor states this is fixed in 1786533565 (unaffected)
Vendor states this is fixed in 1786628667 (unaffected)
Vendor states this is fixed in 1786628681 (unaffected)
Vendor states this is fixed in 1787124632 (unaffected)
Vendor states this is fixed in 1787124635 (unaffected)
Vendor states this is fixed in 1787124779 (unaffected)
Vendor states this is fixed in 1787124925 (unaffected)
Vendor states this is fixed in 1787125069 (unaffected)
Vendor states this is fixed in 1787125166 (unaffected)
Vendor states this is fixed in 1787125311 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (16)

Vendor AdvisoryMailing List
Source: cverecord
https://lists.apache.org/thread/tfmgv86xr0z1y096vs3z0y315t1v3o97
Mailing ListThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/04/22/5
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/security/cve/CVE-2026-40542
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://bugzilla.redhat.com/show_bug.cgi?id=2460518
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:60239
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:60246
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:60247

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.3HIGHCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-304CWE-325

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