# CVE-2026-40479: Kimai: Stored XSS via Incomplete HTML Attribute Escaping in Team Member Widget

> Authenticated users can inject JavaScript via profile aliases, leading to stored XSS and privilege escalation when administrators view team forms.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **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:** 17 Apr 2026
- **Updated:** 20 Apr 2026
- **Also known as:** GHSA-g82g-m9vx-vhjg

## What is CVE-2026-40479?

CVE-2026-40479 is a medium-severity cross-site scripting vulnerability in kimai, published on 17 Apr 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. In versions 1.16.3 through 2.52.0, the escapeForHtml() function in KimaiEscape.js does not escape double quote or single quote characters. When a user's profile alias is inserted into an HTML attribute context via the team member form prototype and rendered through innerHTML, this incomplete escaping allows HTML attribute injection. An authenticated user with ROLE_USER privileges can store a malicious alias that executes JavaScript in the browser of any administrator viewing the team form, resulting in stored XSS with privilege escalation. This issue has been fixed in version 2.53.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-40479?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kimai/kimai` | Packagist | All versions | 2.53.0 |
| `kimai/kimai` | Packagist | All versions | 2.53.0 |

Products: Kimai Kimai.

## How do I fix CVE-2026-40479?

Upgrade kimai/kimai to 2.53.0 or later.

## Is CVE-2026-40479 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40479 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-2026-40479 and fix it if it is affected.

What it is: CVE-2026-40479 is a medium-severity cross-site scripting vulnerability in kimai, published on 17 Apr 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-2026-40479 exists.

Affected packages and fixed versions:
- kimai/kimai (Packagist): affected all versions; fixed in 2.53.0
- kimai/kimai (Packagist): affected all versions; fixed in 2.53.0

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-2026-40479/ (Markdown: https://insights.sbomify.com/CVE-2026-40479/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40479
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40479
- OSV: https://osv.dev/vulnerability/CVE-2026-40479

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40479/
Summaries are generated and may contain mistakes; the official description above is the record.