---
id: "CVE-2026-91981"
kind: "vulnerability"
aliases: ["CVE-2026-91981", "GHSA-vfxw-3x8p-2vjr", "GO-2026-6752"]
title: "Vikunja: Link-share token can enumerate users through the v2 API in code.vikunja.io/api"
severity: "medium"
cvss: 5.3
epss: 0.00306
exploited: false
status: "open"
category: "package"
products: [{"name": "code.vikunja.io/api", "fixed": [], "affected": "all versions", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["go", "package", "self-hosted", "vikunja"]
not_affected_if: ["default-config"]
published_at: "2026-09-15T16:17:55+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T21:49:00+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6752", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91981", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91981", "first_seen_at": "2026-10-23T19:35:23+00:00"}]
---

# Vikunja: Link-share token can enumerate users through the v2 API in code.vikunja.io/api

A Vikunja link-share token, which is meant to give access to a single shared project, can be used to enumerate user accounts through the v2 API. An attacker holding such a token can learn which users exist on the instance.

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

## Affected

- go:code.vikunja.io/api affected all versions fixed ?

## How to check

Check the Vikunja version in use: a Go build of code.vikunja.io/api before v2.6.0 is affected (go version -m on the binary or the go.mod require line).

## Fix

Upgrade code.vikunja.io/api to v2.6.0 or later.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6752
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91981
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91981

## From the sources

Vikunja: Link-share token can enumerate users through the v2 API 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 v2.6.0.

---

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