# CVE-2026-4103: Cross-Site Scripting via HTML Sanitization in WSO2 Publisher and Developer Portals Allows Malicious Script Execution

> Attackers can inject malicious scripts into API documentation viewed in WSO2 Publisher and Developer Portals, potentially hijacking user sessions.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-wfvc-6jjf-4g5g

## What is CVE-2026-4103?

CVE-2026-4103 is a medium-severity cross-site scripting vulnerability in WSO2 API Control Plane, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Insufficient HTML sanitization in the Publisher Portal and Developer Portal allows untrusted user input to be rendered without proper encoding or neutralization. This enables the injection and execution of malicious JavaScript when affected API documents are viewed.

Successful exploitation may result in the execution of malicious scripts within the user's browser context when viewing API documentation. Users with permissions to access the API documentation through these portals may be impacted, potentially allowing attackers to perform actions on behalf of the user, depending on their session privileges.

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

## Which versions are affected by CVE-2026-4103?


## How do I fix CVE-2026-4103?

No fix has been published for CVE-2026-4103 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4103 being exploited?

There is no known exploitation of CVE-2026-4103 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4103 and fix it if it is affected.

What it is: CVE-2026-4103 is a medium-severity cross-site scripting vulnerability in WSO2 API Control Plane, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-4103 in the wild and no public exploit code.

Affected product: WSO2 API Control Plane. 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-2026-4103/ (Markdown: https://insights.sbomify.com/CVE-2026-4103/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4103
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4103
- OSV: https://osv.dev/vulnerability/CVE-2026-4103

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-4103/
Summaries are generated and may contain mistakes; the official description above is the record.