Duplicate Advisory: Vikunja: Link-share token can enumerate users through the v2 API

{
  "id": "5f4e688415c55f0aabf9f9995d4d369e8087478e48b167044693dbcb133b5f18",
  "url": "https://osv.dev/vulnerability/GHSA-vcgv-7rvm-m3vp",
  "method": "structured",
  "payload": {
    "kind": "withdrawal",
    "title": "Duplicate Advisory: Vikunja: Link-share token can enumerate users through the v2 API",
    "summary": "### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-vfxw-3x8p-2vjr. This link is maintained to preserve external references. ### Original Description Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API user search endpoints. Attackers with a read-only share link can enumerate project users via the projects endpoint and confirm arbitrary usernames exist via the global search endpoint.",
    "evidence": "osv:GHSA-vcgv-7rvm-m3vp",
    "products": [
      {
        "name": {
          "value": "code.vikunja.io/api",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-vcgv-7rvm-m3vp",
      "aliases": [
        "GHSA-vcgv-7rvm-m3vp"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
        },
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "2.5.0"
                }
              ]
            }
          ],
          "package": {
            "name": "code.vikunja.io/api",
            "purl": "pkg:golang/code.vikunja.io/api",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-vcgv-7rvm-m3vp/GHSA-vcgv-7rvm-m3vp.json"
          }
        }
      ],
      "modified": "2026-10-09T21:00:07.394329162Z",
      "provider": "osv",
      "references": [
        "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-91981",
        "https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-200"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-09-15T16:17:55Z",
        "github_reviewed_at": "2026-10-09T20:52:33Z"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/1/score"
  },
  "source_id": "core-osv",
  "document_id": 124158,
  "published_at": "2026-09-15T18:32:30+00:00"
}