# CVE-2025-13993: MailerLite – Signup forms (official) <= 1.7.16 - Authenticated (Administrator+) Stored Cross-Site Scripting

> Authenticated administrators can inject arbitrary scripts via signup form parameters, leading to stored XSS execution for other users.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Dec 2025
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-647v-r7p3-c33c

## What is CVE-2025-13993?

CVE-2025-13993 is a medium-severity cross-site scripting vulnerability in MailerLite – Signup forms (official), published on 12 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

The MailerLite – Signup forms (official) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'form_description' and 'success_message' parameters in versions up to, and including, 1.7.16 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator access or higher, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

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

## Which versions are affected by CVE-2025-13993?


## How do I fix CVE-2025-13993?

No fix has been published for CVE-2025-13993 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-13993 being exploited?

There is no known exploitation of CVE-2025-13993 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-13993 and fix it if it is affected.

What it is: CVE-2025-13993 is a medium-severity cross-site scripting vulnerability in MailerLite – Signup forms (official), published on 12 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-13993 in the wild and no public exploit code.

Affected product: MailerLite – Signup forms (official). 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-2025-13993/ (Markdown: https://insights.sbomify.com/CVE-2025-13993/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-13993
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-13993
- OSV: https://osv.dev/vulnerability/CVE-2025-13993

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-13993/
Summaries are generated and may contain mistakes; the official description above is the record.