---
id: "CVE-2026-68581"
kind: "vulnerability"
aliases: ["CVE-2026-68581", "GHSA-vvcv-vpph-h844", "GO-2026-6753"]
title: "Vikunja: Link-share principal ID collision allows cross-account API token issuance and management in code.vikunja.io/api"
severity: "high"
cvss: 8.6
epss: 0.00464
exploited: false
status: "open"
category: "package"
products: [{"name": "code.vikunja.io/api", "fixed": [], "affected": ">= 0.22.0", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["api-tokens", "go", "package", "self-hosted", "vikunja"]
not_affected_if: ["version-2.4.0-or-later", "version-below-0.22.0"]
published_at: "2026-08-02T13:16:54+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T21:44:09+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6753", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-68581", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68581", "first_seen_at": "2026-10-23T19:35:23+00:00"}]
---

# Vikunja: Link-share principal ID collision allows cross-account API token issuance and management in code.vikunja.io/api

Vikunja 0.22.0 through 2.3.0 does not check whether a JWT belongs to a user or a link share, so a link-share ID can match a target user's numeric ID. An authenticated attacker can then list, create and delete that user's API tokens, including tokens with attacker-chosen scopes.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:code.vikunja.io/api affected >= 0.22.0 fixed ?

## How to check

Check whether the running Vikunja version is between 0.22.0 and 2.3.0. The sources do not give a command.

## Fix

Upgrade code.vikunja.io/api to 2.4.0 or later.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6753
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-68581
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-68581

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_