CVE-2026-73294
Received Received - Intake

Command Injection in Semaphore UI

Publication date: 2026-08-12

Last updated on: 2026-08-12

Assigner: GitHub, Inc.

Description
Semaphore UI is a web interface for managing DevOps tools. Prior to 2.18.17 and 2.19.5-beta2, repository git_url handling passes an attacker-controlled --upload-pack option to CmdGitClient.GetLastRemoteCommitHash through POST /api/project/{id}/repositories and scheduled commit-hash polling, allowing a project Manager or Owner to execute arbitrary OS commands in the Semaphore server process. This issue is fixed in versions 2.18.17 and 2.19.5-beta2.

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Meta Information

Published
2026-08-12
Last Modified
2026-08-12
Generated
2026-09-01
AI Q&A
2026-08-12
EPSS Evaluated
2026-08-31
NVD
CVE-2026-73294
EUVD
EUVD-2026-57320

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
semaphoreui semaphore to 2.18.17 (exc)
semaphoreui semaphore 2.18.17
semaphoreui semaphore 2.19.5-beta2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-88 The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

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Executive Summary

This is a critical OS command injection vulnerability in SemaphoreUI affecting versions before 2.18.17 and 2.19.5-beta2. It allows attackers with Manager or Owner roles to execute arbitrary OS commands on the Semaphore server by injecting malicious commands via the git_url parameter using the --upload-pack option in Git commands. The flaw bypasses runner isolation and grants access to the server's master encryption key and all project secrets.

Detection Guidance

Check Semaphore server logs for suspicious Git URL patterns or command injection attempts. Look for URLs starting with hyphens or containing --upload-pack in API requests to /api/project/{id}/repositories. Monitor for unexpected command execution or unauthorized access to encryption keys or secrets.

Impact Analysis

If you use SemaphoreUI with versions before 2.18.17 or 2.19.5-beta2, an attacker with project Manager or Owner permissions could execute arbitrary commands on your Semaphore server. This could lead to full system compromise, data theft, or unauthorized access to sensitive information like encryption keys and project secrets. The attack can be triggered through project schedules or API endpoints.

Compliance Impact

This vulnerability could severely impact compliance with GDPR and HIPAA by enabling unauthorized access to sensitive data. GDPR requires protection of personal data, while HIPAA mandates safeguarding protected health information. A successful exploit could lead to data breaches, resulting in regulatory fines, legal liabilities, and reputational damage for organizations handling regulated data.

Mitigation Strategies

Upgrade Semaphore to version 2.18.17 or 2.19.5-beta2 or later. Apply the ValidateGitURL function and --end-of-options flag fixes to prevent Git option injection. Restrict project Manager and Owner roles to trusted users and review all project schedules for malicious activity.

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