CVE-2026-91983
Received Received - Intake

Vikunja API Token Scope Bypass via Expand Parameter

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: VulnCheck

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.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91983
EUVD
EUVD-2026-78654

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
vikunja vikunja to 2.6.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

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Executive Summary

Vikunja before version 2.6.0 has a vulnerability where API tokens with limited scopes can bypass authorization checks in task read endpoints. By using the expand query parameter, attackers can access sensitive data such as comments, reactions, and time entries without proper permission verification.

Impact Analysis

This vulnerability allows unauthorized users with restricted API tokens to access sensitive information like task comments, reactions, and time entries. This could lead to data leaks, unauthorized modifications, or misuse of confidential data depending on the system's configuration.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. Organizations using affected Vikunja versions may face compliance violations, legal penalties, and reputational damage due to insufficient access controls.

Mitigation Strategies

Immediately upgrade Vikunja to version 2.6.0 or later to address the API token scope bypass vulnerability in task read endpoints.

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