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GHSA-9jrx-vmh8-c6xw

Duplicate Advisory: Vikunja: Link-share principal ID collision allows cross-account API token issuance and management

High Withdrawn Oct 9, 2026 Go
Severity
0.0 / 10
High · CVSS 4.0
Exploit chance (EPSS)
—
No score published
Known exploited
No
Not in CISA's catalog
Weakness
CWE-863 Incorrect Authorization
Fix
None yet
No fixed version published

Description

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-vvcv-vpph-h844. This link is maintained to preserve external references.

Original Description

Vikunja versions 0.22.0 through 2.3.0 fail to validate the principal type in API token management. Because user IDs and link-share IDs are independent numeric sequences and both resolve through a generic web.Auth.GetID() interface, a link-share JWT whose numeric ID equals a target user's ID is treated as that user by the /api/v1/tokens endpoints. An authenticated attacker can obtain a target's numeric user ID via authenticated user search, then create link shares on an attacker-writable project until the link-share sequence reaches that value, and use the resulting link-share JWT to list, create, and delete the target user's API tokens (including issuing a new token with attacker-chosen scopes under the target's permissions). Fixed in version 2.4.0.

Affected versions

Go

PackageVulnerableFixed in
code.vikunja.io/api
>= 0.22.0, <= 2.3.0
No fix yet

How to fix

No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack vector
Network
Attack complexity
Low
Attack requirements
None
Privileges required
Low
User interaction
None
Confidentiality (vulnerable system)
High
Integrity (vulnerable system)
High
Availability (vulnerable system)
None
Confidentiality (subsequent systems)
None
Integrity (subsequent systems)
None
Availability (subsequent systems)
None
Exploit maturity
Not defined
Scope
X

CVSS 3.1 8.1

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

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Weakness

CWE-863: Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

How to prevent it
  • Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
  • Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
  • Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
  • Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
  • System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.

References

Timeline

  1. Published
  2. Withdrawn
  3. Last updated by the source
AdvisorySeverityWhy it's related
GHSA-m687-p538-r5hp
Vikunja: Permissive Cross-domain Security Policy trusts every localhost origin which should not be trusted
Medium Also affects code.vikunja.io/api
GHSA-fmmf-xq98-g327
Vikunja: Write-level project members can delete admin-tier link shares through an unloaded permission check
Medium Also affects code.vikunja.io/api
GHSA-pjr3-86v4-5p7w
Vikunja: Explicit lower-permission share on a sub-project is silently overridden by an inherited parent permission (broken access control / privilege-management regression in v2.6.0)
Medium Also affects code.vikunja.io/api
GHSA-hjx8-qv73-f7cm
Vikunja: Webhooks and link shares survive every revocation path, so a removed collaborator keeps a live feed
High Also affects code.vikunja.io/api
GHSA-fprf-r6rv-xg99
Vikunja: Saved filter creation with an empty filter string recalculates task positions across all tenants
Medium Also affects code.vikunja.io/api
GHSA-4hv6-xc92-j86g
Vikunja: WebSocket authentication ignores server-side session state, so revoked sessions keep receiving live pushes
High Also affects code.vikunja.io/api
GHSA-w2ch-4xgr-22ww
Vikunja: Task relation deletion does not check read access to the other task, allowing cross-project relation removal
Low Also affects code.vikunja.io/api
GHSA-8wvg-r2j4-3737
Vikunja: Assignee email addresses disclosed to read-only project members via the task assignees endpoint
Medium Also affects code.vikunja.io/api
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