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CVE Record

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

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.

HighCVSS 7.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Apache HttpClient 5.6 can accept SCRAM-SHA-256 authentication without correctly confirming the server’s identity. An attacker able to interfere with authentication could undermine trust between an application and the service it contacts, potentially affecting confidentiality, integrity, and availability. Apache recommends upgrading to 5.6.1.

Executive priority

Treat as a high-priority dependency update where HttpClient 5.6 and SCRAM-SHA-256 are confirmed. Accelerate remediation for clients crossing untrusted networks or protecting sensitive transactions. Systems not using version 5.6 or the affected authentication mechanism have lower immediate urgency, subject to inventory confirmation.

Technical view

A missing mutual-authentication verification step affects SCRAM-SHA-256 in Apache HttpClient 5.6. The issue is classified as CWE-304 and CWE-325. Its CVSS 3.1 score is 7.3, reflecting network reachability, low attack complexity, no required privileges, and no user interaction, with limited confidentiality, integrity, and availability impact.

Likely exposure

Exposure is limited to applications containing Apache HttpClient 5.6 that use the affected SCRAM-SHA-256 authentication path. Check direct and transitive dependencies, packaged artifacts, containers, and runtime classpaths. The supplied record identifies other versions as unaffected by default; product-specific Red Hat status should be confirmed through its advisories.

Exploitation context

The supplied record does not identify this CVE as being in KEV, and no provided source reports active exploitation or a public exploit. The CVSS vector indicates a remote, unauthenticated, low-complexity condition without user interaction, but actual exploitability depends on reaching and influencing an affected SCRAM-SHA-256 authentication exchange.

Researcher notes

The defect concerns authentication completeness, not a general HTTP parsing flaw. Investigation should focus on the SCRAM-SHA-256 server-authentication verification path and whether applications rely on its mutual-authentication guarantee. The provided evidence establishes the vulnerable and fixed versions, but does not establish exploitation in the wild or describe affected higher-level products.

Mitigation direction

  • Upgrade Apache HttpClient from 5.6 to 5.6.1 or later.
  • Identify vendor-packaged dependencies and apply the corresponding supported security update.
  • Prioritize internet-facing or trust-sensitive clients using SCRAM-SHA-256.
  • Review vendor guidance before adopting any temporary workaround.

Validation and detection

  • Search dependency manifests, lockfiles, SBOMs, containers, and runtime classpaths for httpclient5 version 5.6.
  • Confirm whether affected applications configure or negotiate SCRAM-SHA-256.
  • Verify deployed instances load version 5.6.1 or a vendor-fixed package.
  • Test that clients reject authentication when mutual verification is incomplete or invalid.
  • Review relevant Red Hat advisories for distribution-specific package status.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-304: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-325: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-40542 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
16Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.3CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4CISA-ADP
7.3CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.3High
CVSS 3.1 vector shape for CVE-2026-40542Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container
redhat-SADPhttpclient: Apache HttpClient: Authentication bypass due to missing mutual authentication verification
other:Red Hat severity ratingcvssV3_1
  • 2026-04-22T08:00:57.407Z: Reported to Red Hat.
  • 2026-04-22T07:07:21.344Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Apache Software FoundationApache HttpClientorg.apache.httpcomponents.client5:httpclient5, 5.6unaffected
Weakness

CWE details

CWE-304CWE-325

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-304 · source CWE mapping

Missing Critical Step in Authentication

Missing Critical Step in Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-325 · source CWE mapping

Missing Cryptographic Step

Missing Cryptographic Step represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs