Vulnerability-Lookup

GHSA-MJ9W-XM4P-H2MP

Vulnerability from github – Published: 2026-10-06 21:31 – Updated: 2026-10-06 21:31

Details

A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported via the GitHub Bug Bounty program.

Severity

6.0 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-103620"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-862"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-06T19:17:39Z",
    "severity": "MODERATE"
  },
  "details": "A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported via the GitHub Bug Bounty program.",
  "id": "GHSA-mj9w-xm4p-h2mp",
  "modified": "2026-10-06T21:31:40Z",
  "published": "2026-10-06T21:31:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-103620"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.16"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.13"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.9"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.7"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.22/admin/release-notes#3.22.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-103620 (GCVE-0-2026-103620)

Vulnerability from cvelistv5 – Published: 2026-10-06 18:56 – Updated: 2026-10-07 16:32

Title

Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL

Summary

Severity

6 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-07 16:31 UTC

CWE

CWE-862 - Missing Authorization

Assigner

GitHub_P CNA under the mitre root

CNA scorecard B 83/100 over 28 records in the last 180 days details

References

5 references

URL	Tags
https://docs.github.com/en/enterprise-server@3.18…	release-notes
https://docs.github.com/en/enterprise-server@3.19…	release-notes
https://docs.github.com/en/enterprise-server@3.20…	release-notes
https://docs.github.com/en/enterprise-server@3.21…	release-notes
https://docs.github.com/en/enterprise-server@3.22…	release-notes

Impacted products

1 product

Vendor	Product	Version
GitHub	Enterprise Server	Affected: 3.18.0 , < 3.18.* (semver) Affected: 3.19.0 , < 3.19.* (semver) Affected: 3.20.0 , < 3.20.* (semver) Affected: 3.21.0 , < 3.21.* (semver) Affected: 3.22.0 , < 3.22.* (semver)

Credits

taise

Show details on NVD website

JSON

To clipboard

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                "timestamp": "2026-10-07T16:31:48.617666Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-MJ9W-XM4P-H2MP

CVE-2026-103620 (GCVE-0-2026-103620)

Tags

Sightings

Nomenclature

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