Vulnerability-Lookup

GHSA-2GR8-2HF5-X695

Vulnerability from github – Published: 2026-04-22 00:31 – Updated: 2026-04-22 00:31

Details

A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to extract sensitive environment variables from the instance through a timing side-channel attack against the notebook rendering service. When private mode was disabled, the notebook viewer followed HTTP redirects without revalidating the destination host, enabling an unauthenticated SSRF to internal services. By chaining this with regex filter queries against an internal API and measuring response time differences, an attacker could infer secret values character by character. Exploitation required that private mode be disabled and that the attacker be able to chain the instance's open redirect endpoint through an external redirect to reach internal services. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5, and 3.20.1. This vulnerability was reported via the GitHub Bug Bounty program.

Severity ?

8.9 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-5921"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-21T23:16:22Z",
    "severity": "HIGH"
  },
  "details": "A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to extract sensitive environment variables from the instance through a timing side-channel attack against the notebook rendering service. When private mode was disabled, the notebook viewer followed HTTP redirects without revalidating the destination host, enabling an unauthenticated SSRF to internal services. By chaining this with regex filter queries against an internal API and measuring response time differences, an attacker could infer secret values character by character. Exploitation required that private mode be disabled and that the attacker be able to chain the instance\u0027s open redirect endpoint through an external redirect to reach internal services.\u00a0This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5, and 3.20.1. This vulnerability was reported via the GitHub Bug Bounty program.",
  "id": "GHSA-2gr8-2hf5-x695",
  "modified": "2026-04-22T00:31:42Z",
  "published": "2026-04-22T00:31:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-5921"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.26"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.21"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.17"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.14"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.8"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.5"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:P/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-2026-5921 (GCVE-0-2026-5921)

Vulnerability from cvelistv5 – Published: 2026-04-21 22:11 – Updated: 2026-04-22 13:18

Title

Server-Side Request Forgery in GitHub Enterprise Server allowed extraction of sensitive environment variables via timing side-channel attack

Summary

Severity ?

8.9 (High)


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

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_P

References

URL

Tags

	https://docs.github.com/en/enterprise-server@3.14…	release-notes
	https://docs.github.com/en/enterprise-server@3.15…	release-notes
	https://docs.github.com/en/enterprise-server@3.16…	release-notes
	https://docs.github.com/en/enterprise-server@3.17…	release-notes
	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

Impacted products

	Vendor	Product	Version
	GitHub	Enterprise Server	Affected: 3.14.0 , < 3.14.26 (semver) Affected: 3.15.0 , < 3.15.21 (semver) Affected: 3.16.0 , < 3.16.17 (semver) Affected: 3.17.0 , < 3.17.14 (semver) Affected: 3.18.0 , < 3.18.8 (semver) Affected: 3.19.0 , < 3.19.5 (semver) Affected: 3.20.0 , < 3.20.1 (semver)

Credits

R31n

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-5921",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-22T13:17:53.690876Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-22T13:18:03.644Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "affected",
          "product": "Enterprise Server",
          "vendor": "GitHub",
          "versions": [
            {
              "changes": [
                {
                  "at": "3.14.26",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.14.26",
              "status": "affected",
              "version": "3.14.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.15.21",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.15.21",
              "status": "affected",
              "version": "3.15.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.16.17",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.16.17",
              "status": "affected",
              "version": "3.16.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.17.14",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.17.14",
              "status": "affected",
              "version": "3.17.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.18.8",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.18.8",
              "status": "affected",
              "version": "3.18.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.19.5",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.19.5",
              "status": "affected",
              "version": "3.19.0",
              "versionType": "semver"
            },
            {
              "changes": [
                {
                  "at": "3.20.1",
                  "status": "unaffected"
                }
              ],
              "lessThan": "3.20.1",
              "status": "affected",
              "version": "3.20.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "R31n"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to extract sensitive environment variables from the instance through a timing side-channel attack against the notebook rendering service. When private mode was disabled, the notebook viewer followed HTTP redirects without revalidating the destination host, enabling an unauthenticated SSRF to internal services. By chaining this with regex filter queries against an internal API and measuring response time differences, an attacker could infer secret values character by character. Exploitation required that private mode be disabled and that the attacker be able to chain the instance\u0027s open redirect endpoint through an external redirect to reach internal services.\u0026nbsp;This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5, and 3.20.1. This vulnerability was reported via the GitHub Bug Bounty program.\u003cbr\u003e\u003cbr\u003e"
            }
          ],
          "value": "A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to extract sensitive environment variables from the instance through a timing side-channel attack against the notebook rendering service. When private mode was disabled, the notebook viewer followed HTTP redirects without revalidating the destination host, enabling an unauthenticated SSRF to internal services. By chaining this with regex filter queries against an internal API and measuring response time differences, an attacker could infer secret values character by character. Exploitation required that private mode be disabled and that the attacker be able to chain the instance\u0027s open redirect endpoint through an external redirect to reach internal services.\u00a0This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5, and 3.20.1. This vulnerability was reported via the GitHub Bug Bounty program."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-462",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-462 Cross-Domain Search Timing"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.9,
            "baseSeverity": "HIGH",
            "exploitMaturity": "PROOF_OF_CONCEPT",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:P",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918 Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-21T22:11:28.950Z",
        "orgId": "82327ea3-741d-41e4-88f8-2cf9e791e760",
        "shortName": "GitHub_P"
      },
      "references": [
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.26"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.21"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.17"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.14"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.8"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.5"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.1"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Server-Side Request Forgery in GitHub Enterprise Server allowed extraction of sensitive environment variables via timing side-channel attack",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "82327ea3-741d-41e4-88f8-2cf9e791e760",
    "assignerShortName": "GitHub_P",
    "cveId": "CVE-2026-5921",
    "datePublished": "2026-04-21T22:11:02.077Z",
    "dateReserved": "2026-04-08T20:59:17.367Z",
    "dateUpdated": "2026-04-22T13:18:03.644Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-2GR8-2HF5-X695

CVE-2026-5921 (GCVE-0-2026-5921)

Tags

Sightings

Nomenclature