Home/CVE/An improper access control vulnerability was identified in GitHub Enterprise Server that allowed authenticated users of
CVE
CVE-2021-22861
An improper access control vulnerability was identified in GitHub Enterprise Server that allowed authenticated users of
An improper access control vulnerability was identified in GitHub Enterprise Server that allowed authenticated users of the instance to gain write access to unauthorized repositories via specifically crafted pull requests and REST API requests. An attacker would need to be able to fork the targeted repository, a setting that is disabled by default for organization owned private repositories. Branch protections such as required pull request reviews or status checks would prevent unauthorized commits from being merged without further review or validation.
This vulnerability affected all versions of GitHub Enterprise Server since 2.4.21 and was fixed in versions 2.20.24, 2.21.15, 2.22.7 and 3.0.1. This vulnerability was reported via the GitHub Bug Bounty program.
MEDIUM · CVSS 6.5
EPSS 0.00324
Monitor
- No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules8
YARA rules0
Look this up elsewhere - one-click external pivots
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How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2021-22861, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
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ATT&CK techniques
12Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.
T1005 · Data from Local System T1012 · Query Registry T1083 · File and Directory Discovery T1134.001 · Token Impersonation/Theft T1550.004 · Web Session Cookie T1552.002 · Credentials in Registry T1562.003 · Impair Command History Logging T1565.002 · Transmitted Data Manipulation T1574.005 · Executable Installer File Permissions Weakness T1574.006 · Dynamic Linker Hijacking T1574.007 · Path Interception by PATH Environment Variable T1574.010 · Services File Permissions Weakness
▤ Build a SIEM detection for these techniques
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CAPEC attack patterns
12Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
CAPEC-CAPEC-1 · Accessing Functionality Not Properly Constrained by ACLs CAPEC-CAPEC-104 · Cross Zone Scripting CAPEC-CAPEC-127 · Directory Indexing CAPEC-CAPEC-13 · Subverting Environment Variable Values CAPEC-CAPEC-17 · Using Malicious Files CAPEC-CAPEC-39 · Manipulating Opaque Client-based Data Tokens CAPEC-CAPEC-402 · Bypassing ATA Password Security CAPEC-CAPEC-45 · Buffer Overflow via Symbolic Links CAPEC-CAPEC-5 · Blue Boxing CAPEC-CAPEC-51 · Poison Web Service Registry CAPEC-CAPEC-59 · Session Credential Falsification through Prediction CAPEC-CAPEC-60 · Reusing Session IDs (aka Session Replay)
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Weakness Classification
CWE-285Improper Authorization
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Affected Products & Versions
4◈
Sigma Hunt Rules
8Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighGithub Push Protection Disabled
producthighGithub Secret Scanning Feature Disabled
producthighGithub High Risk Configuration Disabled
productmediumGithub Repository/Organization Transferred
productmediumGithub SSH Certificate Configuration Changed
productmediumGithub Fork Private Repositories Setting Enabled/Cleared
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Scoring & Timeline
6.5
MEDIUM · CVSS v3.1 · [email protected]
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
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References & Sources
4Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.