# CVE-2026-74793: justhtml before 3.11.0 XSS via selectedcontent projection

> Attackers can inject malicious scripts via SVG or MathML elements in justhtml, leading to cross-site scripting attacks.

- **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:** 23 Aug 2026
- **Updated:** 24 Aug 2026
- **Also known as:** GHSA-gjf2-f4jc-69xf, GHSA-h7rw-29pr-mcj6

## What is CVE-2026-74793?

CVE-2026-74793 is a medium-severity cross-site scripting vulnerability in EmilStenstrom justhtml, published on 23 Aug 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

justhtml before 3.11.0 contains a cross-site scripting vulnerability where the default sanitizer bypasses event handler removal in selectedcontent projections. Attackers can inject SVG or MathML elements with event handlers that are cloned and reinserted into output without sanitization, enabling stored or reflected XSS attacks.

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

## Which versions are affected by CVE-2026-74793?


## How do I fix CVE-2026-74793?

No fix has been published for CVE-2026-74793 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-74793 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74793 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74793 and fix it if it is affected.

What it is: CVE-2026-74793 is a medium-severity cross-site scripting vulnerability in EmilStenstrom justhtml, published on 23 Aug 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-2026-74793 exists.

Affected product: EmilStenstrom justhtml. 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-2026-74793/ (Markdown: https://insights.sbomify.com/CVE-2026-74793/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74793
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74793
- OSV: https://osv.dev/vulnerability/CVE-2026-74793

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74793/
Summaries are generated and may contain mistakes; the official description above is the record.