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CVE-2026-91984 medium CVSS 4.3

Vulnerability in code.vikunja.io/api (CVE-2026-91984)

Summary

Vulnerability in code.vikunja.io/api (CVE-2026-91984). Risk of unauthorized operations or information disclosure. Exploitable via POST /api/v1/tasks/{id}/position. Mitigation: upgrade to 2.6.0 or later.

Original description

The description as published by the source.

Summary

The task-position endpoint authorizes only the task side of the write: TaskPosition.CanUpdate delegates to Task.CanUpdate (write access to the task's own project) and the request body's project_view_id is never validated to belong to the task's project, nor is any access to that view required. Any authenticated user with a single writable task of their own can persist (task_id, project_view_id, position) rows into any other tenant's project view (view IDs are small sequential integers and enumerable). Low position values (below MinPositionSpacing, 0.01) enter the recalculation branch, but RecalculateTaskPositions aborts on its own project read-access check before recalculating and the whole transaction rolls back, so no cross-tenant recalculation actually executes — only the plain row insert (position ≥ 0.01) persists. This is the same root-cause pattern as GHSA-569v-q83c-3j3g (kanban bucket relocation via project_view_id mass-assignment, fixed with a dual-side check for buckets in 2.4.0) surviving in the sibling position endpoint. Verified on Vikunja 2.5.0.

Details

Affected endpoints (both verified):

  • v1: POST /api/v1/tasks/{id}/position
  • v2: PUT /api/v2/tasks/{id}/position

Root cause in pkg/models/task_position.go:

  • CanUpdate (lines 61-64) checks only Task.CanUpdate — i.e. the caller's write access to the task's own project.
  • updateTaskPosition (lines 174-232) upserts (task_id, project_view_id, position) directly; there is n…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-91984 has been found in code.vikunja.io/api.
Attackers can target a specific entry point like POST /api/v1/tasks/{id}/position over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
What to do: upgrade code.vikunja.io/api to 2.6.0 or later.
If unsure, ask your IT team or search "code.vikunja.io/api CVE-2026-91984" on the vendor's site.

CVE-2026-91984 (code.vikunja.io/api) — CWE-639 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/v1/tasks/{id}/position / PUT /api/v2/tasks/{id}/position / POST /projects/{project}/views/{view}/buckets/{bucket}/tasks / TaskPosition.CanUpdate
Patched: 2.6.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-639) exists in code.vikunja.io/api. Attackers reach the vulnerable code path via POST /api/v1/tasks/{id}/position.

📍 Affected scope

Check the vendor advisory for the affected versions of code.vikunja.io/api. Attack surface: POST /api/v1/tasks/{id}/position / PUT /api/v2/tasks/{id}/position / POST /projects/{project}/views/{view}/buckets/{bucket}/tasks / TaskPosition.CanUpdate.

🔥 Severity

Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.6.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual POST /api/v1/tasks/{id}/position requests with malformed payloads or SQL meta-characters. Run grep -r 'code.vikunja.io/api' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'code.vikunja.io/api' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で code.vikunja.io/api を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'POST /api/v1/tasks/{id}/position' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /api/v1/tasks/{id}/position への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply patch patch 
    Upgrade code.vikunja.io/api to 2.6.0

    ステージング環境で 2.6.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。

  4. 4
    Post-deployment verification verify 
    Replay attack against POST /api/v1/tasks/{id}/position on staging to confirm patch closes the vector

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

go code.vikunja.io/api
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.6.0"}]}]

References

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