Vikunja has Broken Access Control on Label Read via SQL Operator Precedence Bug

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-35596: 0.27% estimated exploitation activity in the next 30 days; percentile 19.60 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The hasAccessToLabel function contains a SQL operator precedence bug that allows any authenticated user to read any label that has at least one task association, regardless of project access. Label titles, descriptions, colors, and creator information are exposed. Details The access control query at pkg/models/labelpermissions.go:85-91 uses xorm's query chain in a way that produces SQL without proper grouping: The xorm chain .Where(A OR B).Or(C).And(D) generates SQL: WHERE A OR B OR C AND D. Because SQL AND has higher precedence than OR, this evaluates as WHERE A OR B OR (C AND D). The labels.id = ? constraint (D) only binds to the project access condition (C), while labeltasks.labelid IS NOT NULL (part of A) remains unconstrained. Any label that has at least one task association passes the IS NOT NULL check, regardless of who is requesting it. Proof of Concept Tested on Vikunja v2.2.2. Output: Label IDs are sequential integers, making enumeration straightforward. Impact Any…

Published by the source

10 Apr 2026, 15:33 UTC

Last modified by the source

21 Jul 2026, 14:45 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-hj5c-mhh2-g7jq

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# Patch Next advisory brief: CVE-2026-35596

Advisory: Vikunja has Broken Access Control on Label Read via SQL Operator Precedence Bug
IDs: CVE-2026-35596, GHSA-hj5c-mhh2-g7jq
Record: https://patchnext.com/advisories/cve-2026-35596 (revision 1, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: code.vikunja.io/api 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go code.vikunja.io/api: affected <= 2.2.2; fixed in 2.3.0

## Suggested inspection (read-only)
- Go code.vikunja.io/api: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on code.vikunja.io/api.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-hj5c-mhh2-g7jq (GitHub-reviewed advisory GHSA-hj5c-mhh2-g7jq lists affected ranges: Go code.vikunja.io/api >=0 <=2.2.2)

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