CVE-2021-22864Network attack vector

Authenticated code execution via environment variable override

Published Mar 23, 2021 · Updated Aug 3, 2024

Command injection in GitHub Enterprise Server before 3.0.3 allows remote authenticated users to execute code through GitHub Pages builds. In affected releases, GitHub Pages accepts user-controlled configuration options that override environment variables consumed during a site build. Exploitation requires permission to create and build a Pages site, and successful execution runs on the Enterprise Server instance.

CVSS severity8.8
High
EPSS probability2.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in GitHub Enterprise Server before 3.0.3 allows remote authenticated users to execute code through GitHub Pages builds. In affected releases, GitHub Pages accepts user-controlled configuration options that override environment variables consumed during a site build. Exploitation requires permission to create and build a Pages site, and successful execution runs on the Enterprise Server instance.

The record

CVE
CVE-2021-22864
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
Twitter
Product
GitHub Enterprise Server
Classifications
CWE-77, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.21 <2.21.17
  2. Affected versionversion=2.22 <2.22.9
  3. Affected versionversion=3.0 <3.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Twitter · GitHub Enterprise Serverversion=2.21 <2.21.17; version=2.22 <2.22.9; version=3.0 <3.0.3

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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