CVE-2026-4821

high

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.

References

https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1

https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5

https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8

https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14

https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17

https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21

https://docs.github.com/en/[email protected]/admin/release-notes#3.14.24

Details

Source: Mitre, NVD

Published: 2026-04-21

Updated: 2026-04-21

Risk Information

CVSS v2

Base Score: 9

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 7.2

Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 8.1

Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

Severity: High