# 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.

- **Severity:** Medium 5.4 (`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`)
- **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:** Yes
- **Published:** 8 May 2026
- **Updated:** 8 May 2026
- **Also known as:** GHSA-3xc2-h5r3-wv3r

## 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 (Improper Neutralization of Formula Elements in a CSV File)

## Which versions are affected by CVE-2026-42267?

2 open source packages ship an affected version, including kimai/kimai. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kimai/kimai` | Packagist | From 2.27.0 | 2.54.0 |
| `kimai/kimai` | Packagist | From 2.27.0 | 2.54.0 |

Products: Kimai Kimai.

## How do I fix CVE-2026-42267?

Upgrade kimai/kimai to 2.54.0 or later.

## 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](https://insights.sbomify.com/CVE-2020-19825/): Cross-site Scripting in kimai/kimai (critical 9.6)
- [CVE-2023-53957](https://insights.sbomify.com/CVE-2023-53957/): Kimai 1.30.10 SameSite Cookie Vulnerability Session Hijacking (high 8.5)
- [CVE-2021-43515](https://insights.sbomify.com/CVE-2021-43515/): Improper Neutralization of Formula Elements in a CSV File in Kimai 2 (high 7.8)
- [CVE-2023-46245](https://insights.sbomify.com/CVE-2023-46245/): Kimai (Authenticated) SSTI to RCE by Uploading a Malicious Twig File (high 7.2)
- [CVE-2026-23626](https://insights.sbomify.com/CVE-2026-23626/): Kimai Vulnerable to Authenticated Server-Side Template Injection (SSTI) (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42267 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42267 exists.

Affected packages and fixed versions:
- kimai/kimai (Packagist): affected from 2.27.0; fixed in 2.54.0
- kimai/kimai (Packagist): affected from 2.27.0; fixed in 2.54.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-42267/ (Markdown: https://insights.sbomify.com/CVE-2026-42267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42267
- OSV: https://osv.dev/vulnerability/CVE-2026-42267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42267/
Summaries are generated and may contain mistakes; the official description above is the record.