---
id: CVE-2026-91981
title: >-
  Vikunja versions before 2.6.0 fail to properly validate link-share tokens in
  the v2 API user search endpoints
summary: >-
  Vikunja versions before 2.6.0 fail to properly validate link-share tokens in
  the v2 API user search endpoints. Attackers with a read-only share link can
  enumerate project users via the projects endpoint and confirm arbitrary
  usernames ex…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-200
vendor: go-vikunja
product: vikunja
affected:
  - vikunja < 2.6.0
published: '2026-09-15'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T19:17:16.220'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91981'
references:
  - url: >-
      https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-21T18:47:21.313184Z'
epss: 0.00241
epssPercentile: 0.155
ingestedAt: '2026-09-15T15:39:12.911Z'
---

## Overview

Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API user search endpoints. Attackers with a read-only share link can enumerate project users via the projects endpoint and confirm arbitrary usernames exist via the global search endpoint.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.