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CVE-2026-91985 high CVSS 7.5

Information Disclosure in code.vikunja.io/api (CVE-2026-91985)

Summary

Vulnerability in code.vikunja.io/api (CVE-2026-91985). Confidential information can be exposed externally. Exploitable via POST /shares/{share}/auth. Mitigation: upgrade to 2.6.0 or later.

Original description

The description as published by the source.

Summary

A user who has only read permission on a project can call the single link-share read endpoint and receive the share's hash field — the secret credential that the anonymous POST /shares/{share}/auth endpoint exchanges for a link-share JWT carrying the share's permission (read / read-write / admin). A read-only member can therefore mint a write- or admin-level token for the project and perform writes they are not entitled to, while their own user token is correctly refused. This is the remaining variant of the link-share hash disclosure class: GHSA-8hp8-9fhr-pfm9 fixed the list endpoint (ReadAll now requires project admin) but the single-read endpoint's gate was never aligned. Verified on Vikunja 2.5.0; the weak gate has existed since the endpoint, so earlier versions are likely affected too.

Details

Affected endpoints (both verified with a complete chain):

  • v1: GET /api/v1/projects/{project}/shares/{share}
  • v2: GET /api/v2/projects/{project}/shares/{share}

Permission gate: LinkSharing.CanRead (pkg/models/link_sharing_permissions.go) delegates to project.CanRead(s, a) — i.e. any user with read access to the project passes. The response serializes the hash field (pkg/models/link_sharing.go, field tag json:"hash"), which is the share's bearer credential. The share password field is correctly cleared before returning, but the hash is not restricted.

Inconsistent with the sibling list endpoint GET /projects/{project}/shares (`LinkSharin…

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-2026-91985 has been found in code.vikunja.io/api.
Attackers can target a specific entry point like POST /shares/{share}/auth over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
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-2026-91985" on the vendor's site.

CVE-2026-91985 (code.vikunja.io/api) — CWE-200 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /shares/{share}/auth / GET /api/v1/projects/{project}/shares/{share} / GET /api/v2/projects/{project}/shares/{share} / GET /projects/{project}/shares
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

Information disclosure (CWE-200) exists in code.vikunja.io/api. Attackers reach the vulnerable code path via POST /shares/{share}/auth without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of code.vikunja.io/api. Attack surface: POST /shares/{share}/auth / GET /api/v1/projects/{project}/shares/{share} / GET /api/v2/projects/{project}/shares/{share} / GET /projects/{project}/shares.

🔥 Severity

Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.

🔧 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 /shares/{share}/auth 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 /shares/{share}/auth' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /shares/{share}/auth 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 /shares/{share}/auth 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":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6.0"}]}]

References

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