CVE-2026-91983
## Summary API token permission checks only match the HTTP method and route path. The `expand` query parameter on task read endpoints embeds data from other permission groups (task comments, reactions, time entry counts) without checking whether the token holds those scopes. A token scoped only to `tasks` read permissions can therefore read task comments and reactions it was explicitly not granted. ## Details `models.CanDoAPIRoute` (`pkg/models/api_routes.go`, ~line 440) authorises API tokens purely by comparing `method` and `c.Path()` against the routes stored for each granted permission group. The query string is never consulted. The task read endpoints accept `expand`: - `GET /api/v1/tasks/:task`, `GET /api/v1/tasks` (`pkg/models/tasks.go` ReadOne/ReadAll, `pkg/models/task_collection.go`) - `GET /api/v2/tasks/:id`, `GET /api/v2/tasks`, `GET /api/v2/projects/:project/tasks` (`pkg/routes/api/v2/tasks.go`, `task_collection.go`) Accepted values include `comments`, `comment_count`, `reactions`, `time_entries_count`. `addMoreInfoToTasks` (`pkg/models/tasks.go`, ~line 683) loads and embeds that data. At that layer only a `web.Auth` (the plain owner user, resolved by `auth.GetAuthFromClaims`) is available, so the token's scopes cannot be enforced there either. Result: the `tasks_comments`, `reactions`, and `time_entries` permission groups are advisory for any data reachable through a task expansion. ## Impact A holder of an API token scoped to `tasks: [read_one]` or `tasks: [read_all]` (or `projects_views_tasks: [read_all]`) can read the full bodies of task comments, all reactions, and time entry counts on every task the token owner can access, despite `GET /api/v1|v2/tasks/:task/comments` and the reactions endpoints correctly returning 401 for the same token. The leak is limited to data the token owner can already see, and is read-only. The realistic victim is a user who grants a narrowly scoped token to a third-party integration expecting comments to stay pri
Properties
- ghsa_id
- GHSA-9rg3-v78m-26q8
- severity
- medium
- summary
- Vikunja: API token scopes bypassed via task expand parameter (comments, reactions, time entry counts)
- last_source
- GitHub Advisory Database
- cve_id
- CVE-2026-91983
- signal_observed_at
- 2026-10-10T02:17:04+00:00
- is_ghsa_only
- false
- retrieved_at
- 2026-10-10T02:17:04+00:00
- ghsa_published
- 2026-10-09T20:51:52Z
- source_url
- https://github.com/advisories/GHSA-9rg3-v78m-26q8
- ghsa_updated
- 2026-10-09T20:51:53Z
Related Entities (4)
REPORTED_BY (1)
VULNERABLE_TO (1)
AFFECTS (1)
HAS_WEAKNESS (1)
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