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CVE-2026-91973 high CVSS 7.5

Vulnerability in code.vikunja.io/api (CVE-2026-91973)

Summary

Vulnerability in code.vikunja.io/api (CVE-2026-91973). Confidential information can be exposed externally. Exploitable via POST /api/v1/login. Mitigation: upgrade to 2.6.0 or later.

Original description

The description as published by the source.

Summary

The /dav, /.well-known, and /feeds groups are registered on the root Echo instance with only BasicAuth and no rate limiter. CalDAV BasicAuth accepts the plain account password, so password guessing over /dav is unbounded and never returns 429, while /api/v1/login is throttled from the tenth attempt. The only anti-brute-force control on the instance is therefore bypassable.

Details

pkg/routes/routes.go (~lines 238-249) registers /.well-known, /dav, and /feeds with middleware.BasicAuth(...) and nothing else; registerCalDavRoutes adds no limiter. pkg/routes/caldav/auth.go (~lines 88-93) falls through to user.CheckUserCredentials with the plain account password when no CalDAV token matches. In contrast, /register, /login, etc. are wrapped by unauthRateLimit() — an unconditional 10/min/IP pre-auth floor that ignores ratelimit.enabled (default false).

TOTP-enabled accounts and bot users are correctly refused, so this targets password-only accounts.

PoC (verified at runtime against v2.5.0)

POST /api/v1/login  x25 wrong passwords  -> 429 from attempt 2 (throttled)
PROPFIND /dav/principals/{user}/  x60 wrong passwords  -> 401 x60, 429 x0
GET /feeds/notifications.atom  x30 wrong passwords  -> 401 x30, 429 x0
PROPFIND /dav/... with correct password -> 207 (proves the 401s are real auth failures)

Impact

The anti-brute-force floor guarding /login is entirely absent on /dav, /feeds, and /.well-known, giving an un…

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-2026-91973 has been found in code.vikunja.io/api.
Attackers can target a specific entry point like POST /api/v1/login 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-2026-91973" on the vendor's site.

CVE-2026-91973 (code.vikunja.io/api) — CWE-307 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/v1/login / GET /feeds/notifications.atom / registerCalDavRoutes / user.CheckUserCredentials
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-307) exists in code.vikunja.io/api. Attackers reach the vulnerable code path via POST /api/v1/login without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of code.vikunja.io/api. Attack surface: POST /api/v1/login / GET /feeds/notifications.atom / registerCalDavRoutes / user.CheckUserCredentials.

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

    アクセスログで POST /api/v1/login 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/login 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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