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CVE-2026-91983 medium CVSS 4.3

Authorization Flaw in code.vikunja.io/api (CVE-2026-91983)

Summary

Vulnerability in code.vikunja.io/api (CVE-2026-91983). Risk of unauthorized operations or information disclosure. Exploitable via GET /api/v1/tasks/. Mitigation: upgrade to 2.6.0 or later.

Original description

The description as published by the source.

Summary

API token permission checks only match the HTTP method and route path. The expand query parameter on task read endpoints embeds data from other permission groups (task comments, reactions, time entry counts) without checking whether the token holds those scopes. A token scoped only to tasks read permissions can therefore read task comments and reactions it was explicitly not granted.

Details

models.CanDoAPIRoute (pkg/models/api_routes.go, ~line 440) authorises API tokens purely by comparing method and c.Path() against the routes stored for each granted permission group. The query string is never consulted.

The task read endpoints accept expand:

  • GET /api/v1/tasks/:task, GET /api/v1/tasks (pkg/models/tasks.go ReadOne/ReadAll, pkg/models/task_collection.go)
  • GET /api/v2/tasks/:id, GET /api/v2/tasks, GET /api/v2/projects/:project/tasks (pkg/routes/api/v2/tasks.go, task_collection.go)

Accepted values include comments, comment_count, reactions, time_entries_count. addMoreInfoToTasks (pkg/models/tasks.go, ~line 683) loads and embeds that data. At that layer only a web.Auth (the plain owner user, resolved by auth.GetAuthFromClaims) is available, so the token's scopes cannot be enforced there either.

Result: the tasks_comments, reactions, and time_entries permission groups are advisory for any data reachable through a task expansion.

Impact

A holder of an API token scoped to tasks: [read_one] or `task…

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-2026-91983 has been found in code.vikunja.io/api.
Attackers can target a specific entry point like GET /api/v1/tasks/ 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-2026-91983" on the vendor's site.

CVE-2026-91983 (code.vikunja.io/api) — CWE-863 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: GET /api/v1/tasks/ / GET /api/v1/tasks / GET /api/v2/tasks/ / GET /api/v2/tasks
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

Incorrect authorization (CWE-863) exists in code.vikunja.io/api. Attackers reach the vulnerable code path via GET /api/v1/tasks/.

📍 Affected scope

Check the vendor advisory for the affected versions of code.vikunja.io/api. Attack surface: GET /api/v1/tasks/ / GET /api/v1/tasks / GET /api/v2/tasks/ / GET /api/v2/tasks.

🔥 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 GET /api/v1/tasks/ 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 'GET /api/v1/tasks/' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /api/v1/tasks/ 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 GET /api/v1/tasks/ 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":"1.0.0"},{"fixed":"2.6.0"}]}]

References

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