CVE-2026-31957
Himmelblau-Idm Himmelblau ≤ 3.1.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HSummary
CVE-2026-31957 is a critical-severity Initialization of a Resource with an Insecure Default (CWE-1188) vulnerability in Himmelblau-Idm Himmelblau. Its CVSS base score is 10.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Default Accounts (T1078.001); ranked at the 40th 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 CM-2 (Baseline Configuration) and CM-6 (Configuration Settings) — 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-2026-31957, published on 2026-03-11, affects Himmelblau, an interoperability suite for Microsoft Azure Entra ID and Intune, in versions from 3.0.0 up to but not including 3.1.0. The vulnerability occurs when Himmelblau is deployed without a configured tenant domain in himmelblau.conf, resulting in authentication that is not tenant-scoped. In this mode, the software accepts authentication attempts for arbitrary Entra ID domains by dynamically registering providers at runtime. This behavior, designed for initial or local bootstrap scenarios, introduces risks in remote authentication environments. It carries a CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H) and is associated with CWE-1188.
A network-based attacker requires no privileges, no user interaction, and low attack complexity to exploit this issue. By directing authentication attempts to an affected Himmelblau instance lacking tenant scoping, the attacker can use credentials from arbitrary Entra ID domains, bypassing intended tenant isolation and potentially gaining unauthorized access to the suite's interoperability functions with Entra ID and Intune.
The vulnerability is addressed in Himmelblau version 3.1.0. Additional mitigation guidance is available in the GitHub security advisory at https://github.com/himmelblau-idm/himmelblau/security/advisories/GHSA-q746-m2wv-qh4v.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-11321
Vulnerability Data
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From 3.0.0 to before 3.1.0, if Himmelblau is deployed without a configured tenant domain in himmelblau.conf, authentication is not tenant-scoped. In this mode, Himmelblau can accept authentication attempts…
more
for arbitrary Entra ID domains by dynamically registering providers at runtime. This behavior is intended for initial/local bootstrap scenarios, but it can create risk in remote authentication environments. This vulnerability is fixed in 3.1.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 13 hardening rules · 7 OS baselines
V14.3.2V6.3.2V11.3.1V13.2.3
Mitigating Controls (NIST 800-53 r5) AI
Baseline configuration directly requires documenting and maintaining secure initial settings instead of insecure defaults.
Configuration settings mandate the most restrictive values be applied at initialization, eliminating reliance on insecure factory defaults.
Least privilege reduces the blast radius of any insecure default permissions that remain after initialization.
Security engineering principles include explicit requirements for secure defaults during resource initialization and design.
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.
Hardened baselines and configuration management directly replace insecure defaults with secure settings.
Secure development practices include designing products with secure defaults rather than insecure ones.
Pre-acquisition integrity checks can reject products known to ship with insecure defaults.
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.
Mandating secure baseline templates and immediate replacement of vendor defaults directly stops systems from being deployed with insecure factory settings that attackers can exploit.
Requiring documented specification, testing, and acceptance of changes ensures that new or modified components are not initialized with insecure default settings that would otherwise be left in production.
Requiring suppliers to document secure configuration and implemented security functions reduces the likelihood that products will be initialised with insecure default settings.
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 (1 rule)
- V-248823 OL 8 must not have the telnet-server package installed. prevents CWE-1188
RHEL 7 (1 rule)
- V-204627 SNMP community strings on the Red Hat Enterprise Linux operating system must be changed from the default. prevents CWE-1188
Ubuntu 22.04 (1 rule)
- V-260529 Ubuntu 22.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. prevents CWE-1188
Ubuntu 24.04 (1 rule)
- V-270708 Ubuntu 24.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. prevents CWE-1188
Windows Server 2016 (1 rule)
- V-224972 Active Directory Group Policy objects must have proper access control permissions. prevents CWE-1188
Windows Server 2019 (1 rule)
- V-205741 Windows Server 2019 Active Directory Group Policy objects must have proper access control permissions. prevents CWE-1188