Cross-user Unix impersonation via partial UPN validation
Published May 27, 2026 · Updated May 27, 2026
Authentication bypass in Himmelblau 2.0.0 through 2.3.10 and 3.0.0-alpha through 3.1.4 allows local users to impersonate another Unix account. token_validate accepts the authenticated UPN after comparing only its domain to the requested account, without checking the username local part. Exploitation requires valid credentials in the same configured domain and DAG use; it grants read/write access to the victim's local files and Unix session, not the victim's Entra account.
Summary
What happened
Authentication bypass in Himmelblau 2.0.0 through 2.3.10 and 3.0.0-alpha through 3.1.4 allows local users to impersonate another Unix account. token_validate accepts the authenticated UPN after comparing only its domain to the requested account, without checking the username local part. Exploitation requires valid credentials in the same configured domain and DAG use; it grants read/write access to the victim's local files and Unix session, not the victim's Entra account.
The record
- CVE
- CVE-2026-45108
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- Himmelblau
- Product
- Himmelblau
- Classifications
- CWE-863, T1078
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 2.0.0, < 2.3.11
- Affected versionversion=>= 3.0.0-alpha, < 3.1.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo