Vulnerability-Lookup

GHSA-C6G4-PFHG-GVMP

Vulnerability from github – Published: 2026-08-03 21:31 – Updated: 2026-08-03 21:31

Details

Shlink contains a server-side request forgery vulnerability that allows authenticated API key holders to cause the server to issue arbitrary HTTP GET requests by supplying a crafted long URL during short URL creation with title auto-resolution enabled. Attackers can submit URLs pointing to public hosts that redirect to internal targets, including loopback addresses, link-local ranges, and cloud metadata endpoints such as 169.254.169.254, to exfiltrate internal service information via the HTML title element returned in the short URL creation response.

Severity

5.0 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

5.3 (Medium)


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

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-18736"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-03T21:16:38Z",
    "severity": "MODERATE"
  },
  "details": "Shlink contains a server-side request forgery vulnerability that allows authenticated API key holders to cause the server to issue arbitrary HTTP GET requests by supplying a crafted long URL during short URL creation with title auto-resolution enabled. Attackers can submit URLs pointing to public hosts that redirect to internal targets, including loopback addresses, link-local ranges, and cloud metadata endpoints such as 169.254.169.254, to exfiltrate internal service information via the HTML title element returned in the short URL creation response.",
  "id": "GHSA-c6g4-pfhg-gvmp",
  "modified": "2026-08-03T21:31:38Z",
  "published": "2026-08-03T21:31:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18736"
    },
    {
      "type": "WEB",
      "url": "https://github.com/shlinkio/shlink"
    },
    {
      "type": "WEB",
      "url": "https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/shlink-server-side-request-forgery-via-short-url-title-auto-resolution"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/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-2026-18736 (GCVE-0-2026-18736)

Vulnerability from cvelistv5 – Published: 2026-08-03 20:15 – Updated: 2026-08-04 13:45

Title

Shlink Server-Side Request Forgery via Short URL Title Auto-Resolution

Summary

Severity

5.3 (Medium)


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

5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-04 13:44 UTC

CWE

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

Assigner

VulnCheck

References

3 references

URL	Tags
https://github.com/theopaid/Server-side-request-f…	vendor-advisory
https://github.com/shlinkio/shlink	product
https://www.vulncheck.com/advisories/shlink-serve…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
shlinkio	Shlink	Affected: 2.6.0 , ≤ 5.1.5 (git)

Date Public

2026-08-03 00:00

Credits

Theodosis Paidakis

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-18736",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-04T13:44:56.395426Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-04T13:45:06.977Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "affected",
          "product": "Shlink",
          "vendor": "shlinkio",
          "versions": [
            {
              "lessThanOrEqual": "5.1.5",
              "status": "affected",
              "version": "2.6.0",
              "versionType": "git"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Theodosis Paidakis"
        }
      ],
      "datePublic": "2026-08-03T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "Shlink contains a server-side request forgery vulnerability that allows authenticated API key holders to cause the server to issue arbitrary HTTP GET requests by supplying a crafted long URL during short URL creation with title auto-resolution enabled. Attackers can submit URLs pointing to public hosts that redirect to internal targets, including loopback addresses, link-local ranges, and cloud metadata endpoints such as 169.254.169.254, to exfiltrate internal service information via the HTML title element returned in the short URL creation response."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-03T20:15:22.814Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "GitHub Security Advisory",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/theopaid/Server-side-request-forgery-through-short-URL-title-resolution-shlink-"
        },
        {
          "name": "Product Repository",
          "tags": [
            "product"
          ],
          "url": "https://github.com/shlinkio/shlink"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/shlink-server-side-request-forgery-via-short-url-title-auto-resolution"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Shlink Server-Side Request Forgery via Short URL Title Auto-Resolution",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-18736",
    "datePublished": "2026-08-03T20:15:22.814Z",
    "dateReserved": "2026-08-03T20:03:05.797Z",
    "dateUpdated": "2026-08-04T13:45:06.977Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

GHSA-C6G4-PFHG-GVMP

CVE-2026-18736 (GCVE-0-2026-18736)

Tags

Sightings

Nomenclature