Vulnerability · Published May 8, 2026 · Assigned by GitHub_M

CVE-2026-42267Kimai: Formula Injection via tag names in XLSX export

Medium 5.4

In plain English

A medium-severity security flaw in kimai from kimai. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.4Medium

Exploit odds (30 days)0.2%top 87.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	kimai/kimai	2.54.0	GHSA-3xc2-h5r3-wv3r

Affected products (as reported)

Vendor	Product	Versions
kimai	kimai	>= 2.27.0, < 2.54.0

Weakness: CWE-1236 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

References

https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r x_refsource_CONFIRM
https://github.com/kimai/kimai/releases/tag/2.54.0 x_refsource_MISC