CVE-2026-33312: Code.vikunja.io/api Vikunja Read-only Users Can Delete Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-564f-wx8x-878h",
  "modified" : "2026-03-20T17:25:21Z",
  "published" : "2026-03-20T17:25:21Z",
  "aliases" : [ "CVE-2026-33312" ],
  "summary" : "Vikunja read-only users can delete project background images via broken object-level authorization",
  "details" : "## Summary\n\nThe `DELETE /api/v1/projects/:project/background` endpoint checks `CanRead` permission instead of `CanUpdate`, allowing any user with read-only access to a project to permanently delete its background image.\n\n## Details\n\nThe `RemoveProjectBackground` handler (`pkg/modules/background/handler/background.go`) reuses `checkProjectBackgroundRights`, a helper originally written for the read-only `GetProjectBackground` endpoint. This helper only verifies `CanRead` permission. In contrast, the handler for *setting* a background (`setBackgroundPreparations`) correctly checks `CanUpdate`.\n\nAs a result, destructive write operations (deleting the background file from storage and clearing the project's `background_file_id` and `background_blur_hash` fields) are gated behind a read-only permission check.\n\n## Impact\n\nA user with read-only access to a project — via direct sharing, team membership, link share tokens with read permission, or read-scoped API tokens — can permanently delete the project's background image. The background file is removed from storage and cannot be recovered. This constitutes unauthorized data destruction.\n\n## Reproduction\n\n1. User A creates a project and sets a background image.\n2. User A shares the project with User B with **read-only** permission.\n3. User B sends: `DELETE /api/v1/projects/{project_id}/background` with a valid auth token.\n4. The request succeeds. The background image is permanently deleted.\n\n## References\n\n- `pkg/modules/background/handler/background.go` — `RemoveProjectBackground` (line 416), `checkProjectBackgroundRights` (line 304), `setBackgroundPreparations` (line 106)\n- `pkg/routes/routes.go` line 665 — route registration\n\n## Credits\n\nThis vulnerability was found using [GitHub Security Lab Taskflows](https://github.com/GitHubSecurityLab/seclab-taskflows).",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "code.vikunja.io/api"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.20.2"
      }, {
        "fixed" : "2.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-564f-wx8x-878h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33312"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/go-vikunja/vikunja"
  }, {
    "type" : "WEB",
    "url" : "https://vikunja.io/changelog/vikunja-v2.2.0-was-released"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-20T17:25:21Z",
    "nvd_published_at" : "2026-03-20T15:16:18Z"
  }
}