CVE-2026-42267 Kimai: Formula Injection via tag names in XLSX export
Attackers can inject malicious formulas into XLSX exports via tag names, leading to code execution when admins open the file.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-42267?
CVE-2026-42267 is a medium-severity code injection vulnerability in kimai, published on 8 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, 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. This issue has been patched in version 2.54.0.
Weakness: CWE-1236
Which versions are affected by CVE-2026-42267?
2 open source packages ship an affected version, including kimai/kimai. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
kimai/kimai Packagist | From 2.27.0 | 2.54.0 |
kimai/kimai Packagist | From 2.27.0 | 2.54.0 |
Products include Kimai Kimai.
How do I fix CVE-2026-42267?
Upgrade kimai/kimai to 2.54.0 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-42267 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42267 exists.
Other vulnerabilities in kimai
- CVE-2020-19825 Cross-site Scripting in kimai/kimai
- CVE-2023-53957 Kimai 1.30.10 SameSite Cookie Vulnerability Session Hijacking
- CVE-2021-43515 Improper Neutralization of Formula Elements in a CSV File in Kimai 2
- CVE-2023-46245 Kimai (Authenticated) SSTI to RCE by Uploading a Malicious Twig File
- CVE-2026-23626 Kimai Vulnerable to Authenticated Server-Side Template Injection (SSTI)
Sources
Also known as GHSA-3xc2-h5r3-wv3r.