{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "gogs.io/gogs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.14.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52804"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-193"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-23T16:52:30Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nA repository admin collaborator can escalate their privileges to owner-level access by exploiting an off-by-one error in the `ChangeCollaborationAccessMode` function.\n\n## Vulnerable Code\n\nIn `internal/database/repo_collaboration.go`, line 129:\n\n```go\nfunc (r *Repository) ChangeCollaborationAccessMode(userID int64, mode AccessMode) error {\n    // Discard invalid input\n    if mode \u003c= AccessModeNone || mode \u003e AccessModeOwner {\n        return nil\n    }\n```\n\n`AccessModeOwner` has value 4. The check `mode \u003e AccessModeOwner` evaluates to `4 \u003e 4 = false`, allowing `AccessModeOwner` to pass through. The correct check should be `mode \u003e= AccessModeOwner`.\n\nThe web route at `internal/route/repo/setting.go:413-416` takes the mode as a raw integer from query parameters:\n\n```go\nfunc ChangeCollaborationAccessMode(c *context.Context) {\n    if err := c.Repo.Repository.ChangeCollaborationAccessMode(\n        c.QueryInt64(\"uid\"),\n        database.AccessMode(c.QueryInt(\"mode\"))); err != nil {\n```\n\nThis allows an admin collaborator to POST `mode=4` and escalate to owner.\n\n## Impact\n\nA repository admin collaborator (AccessModeAdmin = 3) can escalate to owner-level access (AccessModeOwner = 4), gaining the ability to:\n- **Delete the repository**\n- **Transfer repository ownership** to another user\n- **Erase wiki data**\n- Perform all other owner-only operations\n\nThe `access` table is also updated (line 181), so the escalated permissions persist across sessions.\n\n## Contrast\n\nThe API route at `internal/route/api/v1/repo_collaborators.go:46` uses `ParseAccessMode()` which only returns Read, Write, or Admin - never Owner. The API endpoint is not affected.\n\n## Steps to Reproduce\n\n1. User A creates a private repository\n2. User A adds User B as a collaborator with **Admin** access (mode=3)\n3. User B logs in and navigates to the repository settings collaboration page\n4. User B sends a POST request:\n   ```\n   POST /{owner}/{repo}/settings/collaboration/access_mode?uid={B_uid}\u0026mode=4\n   ```\n5. User B now has **Owner** access - the \"Danger Zone\" section appears with \"Delete This Repository\" and \"Transfer Ownership\" buttons\n\n## Suggested Fix\n\nChange the validation in `internal/database/repo_collaboration.go` line 129 from:\n```go\nif mode \u003c= AccessModeNone || mode \u003e AccessModeOwner {\n```\nto:\n```go\nif mode \u003c= AccessModeNone || mode \u003e= AccessModeOwner {\n```",
  "id": "GHSA-4565-r4x7-hg8j",
  "modified": "2026-06-23T16:52:30Z",
  "published": "2026-06-23T16:52:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gogs/gogs/security/advisories/GHSA-4565-r4x7-hg8j"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gogs/gogs/pull/8227"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gogs/gogs/commit/1fdc9cc28e159135cfa4d6b11ecd5daa0f8ce22b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gogs/gogs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gogs/gogs/releases/tag/v0.14.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Gogs Vulnerable to Privilege Escalation via Collaboration Access Mode Validation"
}