Vikunja: Assignee email addresses disclosed to read-only project members via the task assignees endpoint

Summary

TaskAssginee.ReadAll returns assignee user objects without blanking the Email field, disclosing assignee email addresses to any read-only project member. Every sibling path that returns user objects obfuscates the email; this one does not.

Details

pkg/models/task_assignees.go (~lines 306-344) does Select("users.*") and returns the result directly. User.Email is json:"email,omitempty", so a non-empty value always serializes. The endpoint gates on task.CanRead, so a read-only member passes. Sibling paths blank the field: pkg/models/tasks.go:530, pkg/models/project_users.go:216, pkg/models/teams.go:177, pkg/models/label_task.go:312, pkg/models/task_attachment.go:511. The omission here reads as an oversight, not a decision.

The same file's getRawTaskAssigneesForTasks (~line 56) also selects users.* but is safe because its only caller (addAssigneesToTasks) blanks the email afterwards.

PoC (verified at runtime against v2.5.0, v1 and v2)

GET /api/v1/tasks/{id}/assignees   (reader with permission:0)
-> [{"id":37,"username":"...","email":"[email protected]", ...}]

Same leak on GET /api/v2/tasks/{id}/assignees (routes through the identical model method). Contrast: GET /api/v1/projects/{id}/projectusers and the project task-embed both return the same users with no email.

Impact

Disclosure of assignees' email addresses to users who should only see usernames. Read-only.

Fix

Blank Email on each returned user in TaskAssginee.ReadAll before returning, matching the sibling paths. Covers v1 and v2 at once.