# CVE-2026-78374: Joomla Extension - joomlart.com - Open mail relay via contact AJAX endpoint in T4 Page Builder extension < 2.3.0

> Unauthenticated attackers can use the contact endpoint to send arbitrary emails, turning the site into an open mail relay.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Sep 2026
- **Updated:** 11 Sep 2026
- **Also known as:** GHSA-3ghv-6pr7-rjxg

## What is CVE-2026-78374?

CVE-2026-78374 is a medium-severity vulnerability in joomlart.com T4 Page Builder extension for Joomla, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Joomla Extension - joomlart.com - Open mail relay via contact AJAX endpoint in T4 Page Builder extension < 2.3.0 - The front-end JSON editor endpoint exposes an action called contact that requires no authentication, no CSRF token, no captcha (when no captcha plugin is enabled) and has no rate limiting. The attacker fully controls the recipient, subject and HTML body, and the mail is sent from the site's configured sender identity (mailfrom/fromname).

Weakness: CWE-201 (Insertion of Sensitive Information Into Sent Data)

## Which versions are affected by CVE-2026-78374?


## How do I fix CVE-2026-78374?

No fix has been published for CVE-2026-78374 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78374 being exploited?

There is no known exploitation of CVE-2026-78374 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78374 and fix it if it is affected.

What it is: CVE-2026-78374 is a medium-severity vulnerability in joomlart.com T4 Page Builder extension for Joomla, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-78374 in the wild and no public exploit code.

Affected product: joomlart.com T4 Page Builder extension for Joomla. 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-2026-78374/ (Markdown: https://insights.sbomify.com/CVE-2026-78374/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78374
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78374
- OSV: https://osv.dev/vulnerability/CVE-2026-78374

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78374/
Summaries are generated and may contain mistakes; the official description above is the record.