# CVE-2026-86833: MetForm < 4.3.1 - Unauthenticated HTML Injection in Notification Emails via Field Shortcodes

> Unauthenticated attackers can inject HTML into MetForm notification emails, potentially leading to XSS attacks against administrators or users.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A: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:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** GHSA-fv77-662p-ggvf

## What is CVE-2026-86833?

CVE-2026-86833 is a medium-severity cross-site scripting vulnerability in Unknown MetForm, published on 7 Oct 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

The MetForm WordPress plugin before 4.3.1 does not sanitize or escape submitted form-field values before inserting them into the HTML body of its email notifications, allowing unauthenticated attackers to inject arbitrary markup into the administrator and submitter notification emails the site sends.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2026-86833?


## How do I fix CVE-2026-86833?

No fix has been published for CVE-2026-86833 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86833 being exploited?

There is no known exploitation of CVE-2026-86833 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86833 and fix it if it is affected.

What it is: CVE-2026-86833 is a medium-severity cross-site scripting vulnerability in Unknown MetForm, published on 7 Oct 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: There is no known exploitation of CVE-2026-86833 in the wild and no public exploit code.

Affected product: Unknown MetForm. 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-2026-86833/ (Markdown: https://insights.sbomify.com/CVE-2026-86833/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86833
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86833
- OSV: https://osv.dev/vulnerability/CVE-2026-86833

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86833/
Summaries are generated and may contain mistakes; the official description above is the record.