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CVE-2026-45108· NVD / CVE Program· CNA GitHub_M

Himmelblau: Authentication Bypass via Cross-User Local Session Impersonation in Device Authorization Grant (DAG) Flow

Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From 2.0.0 to before 3.1.5 and 2.3.11, Himmelblau contained an authentication bypass vulnerability in the Device Authorization Grant (DAG) flow that allowed a user within the same Entra ID domain to obtain a local Unix session as another user by providing their own valid credentials. The vulnerability existed in the token_validate function, which validated domain aliases for legitimate multi-domain scenarios but failed to verify that the local part (username) of the authenticated user's UPN matched the requested account username. The function only compared domains, not the complete usernames. This vulnerability is fixed in 3.1.5 and 2.3.11.

HighCVSS 8.4 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Jun 17, 2026
EPSS
0.4% · 29th percentile
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Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
33 / 40 · 8.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.4
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • himmelblau-idm himmelblau

    • >= 2.0.0, < 2.3.11, >= 3.0.0-alpha, < 3.1.5affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
openSUSE:Leap 16.0himmelblaubefore 2.3.11+git1.116c6763-160000.1.12.3.11+git1.116c6763-160000.1.1
SUSE:Linux Enterprise Server 16.0himmelblaubefore 2.3.11+git1.116c6763-160000.1.12.3.11+git1.116c6763-160000.1.1

Same product

himmelblau-idm: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31957Himmelblau unset domain configuration can allow any-tenant authentication at first login for remote deployments
    40Plan
  • CVE-2026-31979himmelblaud-tasks: local privilege escalation via /tmp symlink attack on Kerberos ccache
    31Monitor
  • CVE-2026-34397himmelblau: NSS fake-primary group lookup reintroduces name collision risk
    28Monitor
  • CVE-2025-54882Himmelblau's Kerberos credential cache collection is world readable
    28Monitor
  • CVE-2025-49012Himmelblau's Name-Based Group Matching in `pam_allow_groups` Leads to Potential Security Bypass
    21Monitor
  • CVE-2025-53013Himmelblau offline auth permits authentication with invalid Hello PIN
    20Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
himmelblau-idm himmelblau3.1.5 · descriptionVendor (CNA)
opensuse:himmelblau2.3.11+git1.116c6763-160000.1.1 · openSUSE:Leap 16.0Package registry (OSV)
suse:himmelblau2.3.11+git1.116c6763-160000.1.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
low · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
Low

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records