# CVE-2026-91983

## Summary

- **CVE ID:** CVE-2026-91983
- **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-863
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## Description

Vikunja before 2.6.0 contains an API token scope bypass vulnerability in task read endpoints where authorization fails to inspect query string parameters. Attackers with limited token scopes can use the expand parameter to access restricted data like comments, reactions, and time entries without proper permission verification.

## Affected Products

- go-vikunja — vikunja (1.0.0)
- go-vikunja — vikunja (2.6.0)

## References

- [CNA](https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9rg3-v78m-26q8)
- [CNA](https://www.vulncheck.com/advisories/vikunja-before-2.6.0-api-token-scope-bypass-via-expand-parameter)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.27%
- **EPSS Percentile:** 19.3

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