Vulnerability in kimai/kimai (CVE-2026-42267)
Summary
Vulnerability in kimai/kimai (CVE-2026-42267). Data can be tampered with by attackers. Exploitable via POST /api/tags. Mitigation: upgrade to 2.54.0 or later.
Original description
The description as published by the source.
Summary
Any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing SUM(54+51) into the XLSX archive. Excel evaluates the formula when the file is opened.
Details
1. ArrayFormatter does not sanitize before returning
sanitizeDDE() exists on StringHelper and is called by TextFormatter, but ArrayFormatter never calls it.
// src/Export/Package/CellFormatter/ArrayFormatter.php:24
return implode(', ', $value); // no sanitizeDDE() call
2. Tag name validation does not block formula trigger characters
The API blocks commas in tag names but permits =, +, -, and @ - all valid formula prefixes in Excel and LibreOffice Calc.
3. OpenSpout silently promotes strings to formula cells
Cell::fromValue("=SUM(54+51)") returns a FormulaCell with no warning.
PoC
- It logs in as normal user, creates tag
=SUM(54+51), assigns it to a timesheet. - Admin has to export timesheets to Excel version via
/en/export/endpoint.
Impact
- Any
ROLE_USERcan plant a formula that executes on the workstation of any user who exports and opens timesheet data - A single malicious tag poisons all future exports across all users and date ranges until the ta…
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-2026-42267 has been found in kimai/kimai.
Attackers can target a specific entry point like POST /api/tags over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 5.7/10.
What to do: upgrade kimai/kimai to 2.54.0 or later.
If unsure, ask your IT team or search "kimai/kimai CVE-2026-42267" on the vendor's site.
CVE-2026-42267 (kimai/kimai) — CWE-1236 / CVSS v3 5.7
Attack vector: remote (network-reachable)
Attack surface: POST /api/tags / ROLE_USER / FormulaCell / ArrayFormatter
Patched: 2.54.0 — 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.
A vulnerability (CWE-1236) exists in kimai/kimai. Attackers reach the vulnerable code path via POST /api/tags.
Check the vendor advisory for the affected versions of kimai/kimai. Attack surface: POST /api/tags / ROLE_USER / FormulaCell / ArrayFormatter.
Severity: Medium (CVSS 5.7/10). Data can be tampered with by attackers.
Update to 2.54.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/tags requests with malformed payloads or SQL meta-characters. Run grep -r 'kimai/kimai' . 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
-
1Identify exposure identify
grep -r 'kimai/kimai' . | 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
kimai/kimaiを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/tags' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/tags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。 -
3Apply patch patch
Upgrade kimai/kimai to 2.54.0ステージング環境で 2.54.0 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。
-
4Post-deployment verification verify
Replay attack against POST /api/tags 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com