Kimai vulnerable to formula Injection via tag names in XLSX exportGHSA-3xc2-h5r3-wv3r
MEDIUMGHSA-3xc2-h5r3-wv3r is a medium-severity (CVSS 5.7) CWE-1236 vulnerability in kimai/kimai. A fix is available for kimai/kimai — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-3xc2-h5r3-wv3r.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
kimai/kimaiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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 <f>SUM(54+51)</f> 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 tag is deleted
Fixes
- Prevent
=being part of the tag name (and other fields as well) - Use OpenSpout
TextCellfor everything that is a string
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | kimai/kimai | ≥ 2.27.0&&< 2.54.0 | 2.54.0composer require kimai/kimai:^2.54.0 |
Affected Products
kimaikimaiDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kimai/kimai, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update kimai/kimai to 2.54.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3xc2-h5r3-wv3r is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-3xc2-h5r3-wv3r in your dependencies?
Find it across Packagist, including transitive dependencies.