API Token Scope Bypass Vulnerability in Vikunja by Vikunja Team
CVE-2026-91983

5.3MEDIUM

Key Information:

Vendor

Go-vikunja

Status
Vikunja
Vendor
CVE Published:
15 September 2026

What is CVE-2026-91983?

Vikunja versions prior to 2.6.0 are susceptible to an API token scope bypass vulnerability within their task read endpoints. This flaw arises due to insufficient inspection of query string parameters during authorization checks. As a result, attackers with restricted token scopes can exploit this vulnerability using the 'expand' parameter to retrieve sensitive data, such as comments, reactions, and time entries, without the necessary permissions. This significant security oversight underlines the importance of robust authorization measures in API design.

Affected Version(s)

vikunja 1.0.0 < 2.6.0

vikunja 2.6.0

References

https://github.com/go-vikunja/vikunja/security/advisories...
vendor-advisory
https://www.vulncheck.com/advisories/vikunja-before-2.6.0...
third-party-advisory

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.