CVE-2026-91981 Vikunja before 2.6.0 User Enumeration via v2 API
Attackers with read-only share links can enumerate project users and confirm arbitrary usernames via the v2 API.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-91981?
CVE-2026-91981 is a medium-severity vulnerability in go-vikunja vikunja, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-200
Which versions are affected by CVE-2026-91981?
3 open source packages ship an affected version, including code.vikunja.io/api.
| Package | Affected | Fixed in |
|---|---|---|
code.vikunja.io/api Go | All versions | None |
code.vikunja.io/api Go | All versions | 2.6.0 |
code.vikunja.io/api Go | All versions | 2.6.0 |
How do I fix CVE-2026-91981?
Upgrade code.vikunja.io/api to 2.6.0 or later.
Is CVE-2026-91981 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91981 exists.
Sources
Also known as GHSA-vfxw-3x8p-2vjr, GO-2026-6752.