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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.

PUBLISHED Reserved 2026-03-25 | Published 2026-04-21 | Updated 2026-04-22 | Assigner GitHub_P




HIGH: 8.1CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

Problem types

CWE-78 Improper neutralization of special elements used in an OS command ('OS command injection')

Product status

Default status
affected

3.20.0 (semver) before 3.20.1
affected

3.19.0 (semver)
affected

3.18.0 (semver)
affected

3.17.0 (semver)
affected

3.16.0 (semver)
affected

3.15.0 (semver)
affected

3.14.0 (semver)
affected

Credits

Seokchan Yoon reporter

References

docs.github.com/...nterprise-server@3.20/admin/release-notes

docs.github.com/...nterprise-server@3.19/admin/release-notes

docs.github.com/...nterprise-server@3.18/admin/release-notes

docs.github.com/...nterprise-server@3.17/admin/release-notes

docs.github.com/...nterprise-server@3.16/admin/release-notes

docs.github.com/...nterprise-server@3.15/admin/release-notes

docs.github.com/...nterprise-server@3.14/admin/release-notes

cve.org (CVE-2026-4821)

nvd.nist.gov (CVE-2026-4821)

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