# Vikunja API token scope bypass via task expand parameter

Source: https://junglewise.ai/threats/duplicate-advisory-vikunja-api-token-scopes-bypassed-via-task-expand-3becbdd0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-10-09  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 4.3 · Published 2026-09-15

Vikunja is a task and project management application with an API that uses tokens with granular permission scopes. A vulnerability allows attackers with limited token scopes to bypass authorization checks by using query parameters to expand and access restricted data like task comments, reactions, and time entry counts that the token should not permit.

Technologies: [code.vikunja.io/api (Go)](https://junglewise.ai/threats/technologies/code-vikunja-io-api), [Vikunja API](https://junglewise.ai/threats/technologies/vikunja-api). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Vikunja](https://junglewise.ai/threats/vendors/vikunja).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 4.3, published 15 September 2026.

**Which products and versions are affected?** code.vikunja.io/api (Go) >= 1.0.0, <= 2.5.0; Vikunja API 1.0.0 to 2.5.0.

**Is there a fix for This vulnerability?** Yes: fixed in 2.6.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run code.vikunja.io/api (Go) or Vikunja API at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2.6.0

## Technical details

The vulnerability exists in Vikunja's API token authorization layer (models.CanDoAPIRoute) which only checks HTTP method and route path, ignoring query string parameters. Task read endpoints accept an expand parameter that embeds data from other permission groups (comments, reactions, time_entries) without verifying the token holds those scopes. An attacker with a token scoped only to tasks:read can use expand=comments or expand=reactions to retrieve restricted data that direct API calls to /comments or /reactions endpoints would deny.

## Affected products

- Vikunja API 1.0.0 to 2.5.0

## Timeline

- 2026-08-31: disclosed
- 2026-09-15: advisory

## References

- [https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9rg3-v78m-26q8](https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9rg3-v78m-26q8)

## Related threats

- [Vikunja CalDAV relation creation bypasses authorization](https://junglewise.ai/threats/go-2026-6732-vikunja-caldav-relation-creation-bypasses-taskrelation-65a4724c)
- [Vikunja task relation deletion missing authorization check](https://junglewise.ai/threats/go-2026-6754-vikunja-task-relation-deletion-does-not-check-read-access-9f93429b)
- [Vikunja cross-project task disclosure through subtask expansion](https://junglewise.ai/threats/go-2026-6714-vikunja-cross-project-task-disclosure-through-subtask-cba3685c)
- [Vikunja information disclosure in task assignees endpoint](https://junglewise.ai/threats/go-2026-6723-vikunja-assignee-email-addresses-disclosed-to-read-only-e328c145)
- [Vikunja permissive CORS configuration account takeover](https://junglewise.ai/threats/cve-2026-111922-vikunja-from-2-2-0-before-2-7-0-contains-a-permissive-cors)