# CVE-2026-40126: DOM-based Cross-Site Scripting in OutSystems Service Center

> A low-privileged attacker can execute arbitrary JavaScript in the victim's browser by uploading a file with a malicious filename in OutSystems Service Center.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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:** No
- **Published:** 17 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-wpg4-f3mj-hxh3

## What is CVE-2026-40126?

CVE-2026-40126 is a medium-severity cross-site scripting vulnerability in OutSystems Service Center, published on 17 Aug 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

OutSystems Service Center is vulnerable to a DOM-based Cross-Site Scripting (XSS) attack that can be exploited by a low-privileged attacker via the upload of a file with a malicious filename containing JavaScript code. The vulnerability exists in all locations where a file can be attached and prepared for upload to the server.

This issue was fixed in OutSystems Service Center version 11.41.2

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

## Which versions are affected by CVE-2026-40126?


## How do I fix CVE-2026-40126?

No fix has been published for CVE-2026-40126 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40126 being exploited?

There is no known exploitation of CVE-2026-40126 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40126 and fix it if it is affected.

What it is: CVE-2026-40126 is a medium-severity cross-site scripting vulnerability in OutSystems Service Center, published on 17 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-40126 in the wild and no public exploit code.

Affected product: OutSystems Service Center. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-40126/ (Markdown: https://insights.sbomify.com/CVE-2026-40126/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40126
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40126
- OSV: https://osv.dev/vulnerability/CVE-2026-40126

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40126/
Summaries are generated and may contain mistakes; the official description above is the record.