Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LSummary
CVE-2026-40542 is a high-severity Missing Critical Step in Authentication (CWE-304) vulnerability in Apache Httpclient. Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 38th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to IA-2 (Identification and Authentication (Organizational Users)) and IA-5 (Authenticator Management) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-40542 affects Apache HttpClient version 5.6, where a missing critical step in authentication allows an attacker to cause the client to accept SCRAM-SHA-256 authentication without proper mutual authentication verification. Published on 2026-04-22, this vulnerability is tracked under CWE-304 and carries a CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L), indicating high severity due to its network accessibility and low attack complexity.
A remote, unauthenticated attacker can exploit this over the network without requiring user interaction or privileges. By manipulating the authentication process, the attacker can trick the client into accepting SCRAM-SHA-256 credentials lacking mutual verification, potentially leading to low-level impacts on confidentiality, integrity, and availability, such as unauthorized acceptance of potentially forged authentication.
Apache advisories recommend upgrading to version 5.6.1, which fixes the issue by restoring proper mutual authentication verification. Additional details are provided in the Apache mailing list thread at https://lists.apache.org/thread/tfmgv86xr0z1y096vs3z0y315t1v3o97 and the OSS-Security announcement at http://www.openwall.com/lists/oss-security/2026/04/22/5.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24630
Vulnerability Data
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 20 hardening rules · 6 OS baselines
V7.2.4
Mitigating Controls (NIST 800-53 r5) AI
IA-2 requires unique identification and authentication of users, directly mandating that all critical authentication steps be performed rather than skipped.
IA-8 requires unique identification and authentication of non-organizational users, ensuring the full authentication process is executed without missing steps.
Requires selection and implementation of specific approved cryptographic algorithms and methods, reducing the chance that an incomplete algorithm is used.
IA-5 enforces proper authenticator lifecycle steps (verification, distribution, revocation) so that no required step in the authentication technique is omitted.
Mandates developer testing and evaluation that can uncover missing cryptographic steps through functional and penetration testing.
AC-3 enforces access decisions only after approved authentication has completed, making skipped authentication steps ineffective.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Requiring complete authentication (e.g., MFA, password policy) directly stops omission of critical steps in the auth process.
Secure SDLC practices explicitly include correct cryptographic algorithm implementation and testing.
Proper identity proofing and credential binding prevents skipping enrollment steps that weaken authentication.
Proper encryption of data-at-rest requires all algorithm steps; omitting one directly weakens the control.
Proper encryption of data-in-transit requires all algorithm steps; omitting one directly weakens the control.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Mandates secure authentication mechanisms, explicitly addressing missing steps in authentication flows.
Directly requires secure management of authentication credentials and processes, preventing skipped critical steps.
Security testing can detect incomplete crypto implementations but does not itself enforce correct algorithm steps.
Mandates correct use of cryptographic controls, directly preventing omission of required algorithm steps.
Secure development lifecycle can catch missing auth steps during design, but does not directly enforce runtime authentication.
Application security requirements may specify complete auth flows, but the control itself is broader.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248524 OL 8 must implement NIST FIPS-validated cryptography for the following: To provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-325
- V-248535 The OL 8 shadow password suite must be configured to use a sufficient number of hashing rounds. prevents CWE-325
Oracle Linux 9 (1 rule)
- V-271454 OL 9 must enable FIPS mode. prevents CWE-325
RHEL 7 (3 rules)
- V-204425 The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon does not allow authentication using an empty password. prevents CWE-304
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. prevents CWE-304
- V-204497 The Red Hat Enterprise Linux operating system must implement NIST FIPS-validated cryptography for the following: to provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-325
RHEL 8 (1 rule)
- V-230223 RHEL 8 must implement NIST FIPS-validated cryptography for the following: To provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-325
Ubuntu 22.04 (2 rules)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-304
- V-260650 Ubuntu 22.04 LTS must implement NIST FIPS-validated cryptography to protect classified information and for the following: To provision digital signatures, to generate cryptographic hashes, and to protect unclassified information requiring confidentiality and cryptographic protection in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-325
Ubuntu 24.04 (1 rule)
- V-270744 Ubuntu 24.04 LTS must implement NIST FIPS-validated cryptography to protect classified information and for the following: To provision digital signatures, to generate cryptographic hashes, and to protect unclassified information requiring confidentiality and cryptographic protection in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-325