CVE-2026-42267: kimai — Exploit & Fix

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.

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CVSS v3.1 Score

5.7

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1236 CWE-1236

Affected Products

Vendor	Product	Versions
kimai	kimai	2.27.0 — 2.54.0

References

Advisories & Patches

https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r

Exploits

https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r

Other References

https://github.com/kimai/kimai/releases/tag/2.54.0

Frequently Asked Questions

What is CVE-2026-42267? +

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. It has a CVSS v3.1 base score of 5.7 (MEDIUM).

How severe is CVE-2026-42267? +

CVE-2026-42267 has a CVSS v3.1 score of 5.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0003, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42267? +

CVE-2026-42267 affects products from kimai, specifically: kimai. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42267? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-42267