# CVE-2026-91981

## Summary

- **CVE ID:** CVE-2026-91981
- **Severity:** MEDIUM
- **CVSS Score:** 5.3 (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)
- **CWE:** CWE-200
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## 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.

## Affected Products

- go-vikunja — vikunja (0)
- go-vikunja — vikunja (2.6.0)

## References

- [CNA](https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr)
- [CNA](https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 15.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._