CVE-2026-42267: Kimai vulnerable to formula Injection via tag names in XLSX export

May 5, 2026

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.

References

github.com/advisories/GHSA-3xc2-h5r3-wv3r
github.com/kimai/kimai
github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r
nvd.nist.gov/vuln/detail/CVE-2026-42267

Code Behaviors & Features

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