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Advisory record · GHSA-vfxw-3x8p-2vjr

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

CVSS 5.3 MediumEPSS 0.0031 · 23rd percentile

Published by the GitHub Advisory Database at 9 Oct 2026, 20:52 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
code.vikunja.io/apiGo<2.6.02.6.0
Identifiers
GHSA-vfxw-3x8p-2vjr · CVE-2026-91981 · GO-2026-6752
Weakness (CWE)
CWE-200 · CWE-863
Tags
Published
9 Oct 2026
Updated
19 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Vikunja versions before 2.6.0 let a link-share token call two v2 user-search endpoints that v1 correctly blocks. A holder of a share link can list the members of the shared project and its parent projects, and can check whether any username exists on the instance. Emails are not exposed. Upgrade to Vikunja 2.6.0 or later, which rejects link-share tokens on these endpoints. The source gives no other workaround.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
5.3 Medium 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0031, the 23rd percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:11 UTC First seen by agentprime
  2. 31 Oct 2026, 14:11 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.