CVE-2026-4821
Proxy configuration command injection vulnerability found in GitHub Enterprise Server Management Console configuration API
Description
An improper neutralization of special elements vulnerability was identified in GitHub Enterprise Server that allowed an authenticated Management Console administrator to execute arbitrary OS commands via shell metacharacter injection in proxy configuration fields such as http_proxy. Exploitation of this vulnerability required access to the GitHub Enterprise Server instance and administrator privileges to the Management Console. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.
INFO
Published Date :
April 21, 2026, 11:16 p.m.
Last Modified :
April 29, 2026, 12:36 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 82327ea3-741d-41e4-88f8-2cf9e791e760 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update GitHub Enterprise Server to version 3.20.1 or later.
- Apply patches for versions 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, or 3.14.26.
- Ensure proxy configuration fields are properly validated.
Public PoC/Exploit Available at Github
CVE-2026-4821 has a 3 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-4821.
| URL | Resource |
|---|---|
| https://docs.github.com/en/[email protected]/admin/release-notes#3.14.24 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5 | Release Notes Vendor Advisory |
| https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1 | Release Notes Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-4821 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-4821
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
GHES CVE Scanner — Defensive security tool for detecting CVE-2026-3854 (Git Push RCE) and CVE-2026-4821 (Management Console proxy injection) in GitHub Enterprise Server. Zero external dependencies, Python 3.8+.
Python
None
📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
security cve exploit poc vulnerability
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-4821 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-4821 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Apr. 29, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions up to (excluding) 3.14.26 *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions from (including) 3.15.0 up to (excluding) 3.15.21 *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions from (including) 3.16.0 up to (excluding) 3.16.17 *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions from (including) 3.17.0 up to (excluding) 3.17.14 *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions from (including) 3.18.0 up to (excluding) 3.18.8 *cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* versions from (including) 3.19.0 up to (excluding) 3.19.5 *cpe:2.3:a:github:enterprise_server:3.20.0:*:*:*:*:*:*:* Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.14.24 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5 Types: Release Notes, Vendor Advisory Added Reference Type GitHub, Inc. (Products Only): https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1 Types: Release Notes, Vendor Advisory -
New CVE Received by [email protected]
Apr. 21, 2026
Action Type Old Value New Value Added Description An improper neutralization of special elements vulnerability was identified in GitHub Enterprise Server that allowed an authenticated Management Console administrator to execute arbitrary OS commands via shell metacharacter injection in proxy configuration fields such as http_proxy. Exploitation of this vulnerability required access to the GitHub Enterprise Server instance and administrator privileges to the Management Console. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program. Added CVSS V4.0 AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-78 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.14.24 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5 Added Reference https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1