CVE-2026-4821: CWE-78 Improper neutralization of special elements used in an OS command ('OS command injection') in GitHub Enterprise Server
CVE-2026-4821 is a high-severity OS command injection vulnerability in GitHub Enterprise Server that affects versions prior to 3. 21. It allows an authenticated Management Console administrator to execute arbitrary operating system commands via shell metacharacter injection in proxy configuration fields such as http_proxy. Exploitation requires both access to the GitHub Enterprise Server instance and administrator privileges to the Management Console. The vulnerability was fixed in versions 3. 20. 1, 3. 19. 5, 3. 18.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-4821) involves improper neutralization of special elements used in OS commands (CWE-78) within GitHub Enterprise Server. Specifically, an authenticated administrator can inject shell metacharacters into proxy configuration fields, such as http_proxy, leading to arbitrary OS command execution. The issue affects all versions prior to 3.21 and requires high privileges (Management Console administrator) and local access to the server instance. The vulnerability was responsibly disclosed via the GitHub Bug Bounty program and has been fixed in multiple patched versions starting from 3.14.26 up to 3.20.1.
Potential Impact
Successful exploitation allows an authenticated Management Console administrator to execute arbitrary OS commands on the underlying server, potentially compromising the server's integrity and confidentiality. This could lead to unauthorized system control or data exposure. However, exploitation requires both administrative privileges and access to the GitHub Enterprise Server instance, limiting the attack surface. There are no reports of active exploitation in the wild.
Mitigation Recommendations
A fix is available and has been released in GitHub Enterprise Server versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. Users should upgrade affected GitHub Enterprise Server instances to one of these patched versions or later to remediate this vulnerability. Since this is not a cloud service, remediation depends on applying these updates. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-4821: CWE-78 Improper neutralization of special elements used in an OS command ('OS command injection') in GitHub Enterprise Server
Description
CVE-2026-4821 is a high-severity OS command injection vulnerability in GitHub Enterprise Server that affects versions prior to 3. 21. It allows an authenticated Management Console administrator to execute arbitrary operating system commands via shell metacharacter injection in proxy configuration fields such as http_proxy. Exploitation requires both access to the GitHub Enterprise Server instance and administrator privileges to the Management Console. The vulnerability was fixed in versions 3. 20. 1, 3. 19. 5, 3. 18.
CVSS v4.0
Score 8.1high
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-4821) involves improper neutralization of special elements used in OS commands (CWE-78) within GitHub Enterprise Server. Specifically, an authenticated administrator can inject shell metacharacters into proxy configuration fields, such as http_proxy, leading to arbitrary OS command execution. The issue affects all versions prior to 3.21 and requires high privileges (Management Console administrator) and local access to the server instance. The vulnerability was responsibly disclosed via the GitHub Bug Bounty program and has been fixed in multiple patched versions starting from 3.14.26 up to 3.20.1.
Potential Impact
Successful exploitation allows an authenticated Management Console administrator to execute arbitrary OS commands on the underlying server, potentially compromising the server's integrity and confidentiality. This could lead to unauthorized system control or data exposure. However, exploitation requires both administrative privileges and access to the GitHub Enterprise Server instance, limiting the attack surface. There are no reports of active exploitation in the wild.
Mitigation Recommendations
A fix is available and has been released in GitHub Enterprise Server versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. Users should upgrade affected GitHub Enterprise Server instances to one of these patched versions or later to remediate this vulnerability. Since this is not a cloud service, remediation depends on applying these updates. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_P
- Date Reserved
- 2026-03-25T13:55:26.048Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69e7faaa19fe3cd2cd0014a4
Added to database: 4/21/2026, 10:31:06 PM
Last enriched: 4/29/2026, 11:44:44 AM
Last updated: 6/4/2026, 7:33:23 PM
Views: 262
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