# CVE-2026-34416: OSCAL-GUI Reflected XSS via project parameter in oscal.php

> Unauthenticated attackers can execute arbitrary JavaScript in victims' browsers via a malicious URL in OSCAL-GUI.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 9 Jun 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-6cgq-85j5-m2j8

## What is CVE-2026-34416?

CVE-2026-34416 is a medium-severity cross-site scripting vulnerability in brian-ruf OSCAL-GUI, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

OSCAL-GUI contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to execute arbitrary JavaScript in a victim's browser by injecting malicious input through the project request parameter. Attackers can craft a malicious URL containing unsanitized input that breaks out of the JavaScript string and HTML attribute context in the body onload event handler to execute arbitrary scripts when the link is visited by a victim.

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

## Which versions are affected by CVE-2026-34416?


## How do I fix CVE-2026-34416?

No fix has been published for CVE-2026-34416 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34416 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34416 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34416 and fix it if it is affected.

What it is: CVE-2026-34416 is a medium-severity cross-site scripting vulnerability in brian-ruf OSCAL-GUI, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, 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-2026-34416 exists.

Affected product: brian-ruf OSCAL-GUI. 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-2026-34416/ (Markdown: https://insights.sbomify.com/CVE-2026-34416/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34416
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34416
- OSV: https://osv.dev/vulnerability/CVE-2026-34416

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-34416/
Summaries are generated and may contain mistakes; the official description above is the record.