# CVE-2023-6621: Post SMTP < 2.8.7 - Reflected Cross-Site Scripting

> Reflected XSS in POST SMTP plugin allows attackers to execute scripts against admin users, potentially leading to account takeover.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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:** 3 Jan 2024
- **Updated:** 18 Jun 2025
- **Also known as:** GHSA-gr9g-7x3w-8vjj

## What is CVE-2023-6621?

CVE-2023-6621 is a medium-severity cross-site scripting vulnerability in Unknown POST SMTP, published on 3 Jan 2024. 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 POST SMTP WordPress plugin before 2.8.7 does not sanitise and escape the msg parameter before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin.

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

## Which versions are affected by CVE-2023-6621?

It affects 1 product.


Products: Wpexperts Post Smtp.

## How do I fix CVE-2023-6621?

No fix has been published for CVE-2023-6621 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-6621 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-6621 exists.

## Other vulnerabilities in Unknown POST SMTP

- [CVE-2023-6875](https://insights.sbomify.com/CVE-2023-6875/): Auth bypass in Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App (critical 9.8)
- [CVE-2023-3179](https://insights.sbomify.com/CVE-2023-3179/): POST SMTP Mailer < 2.5.7 - Account Takeover via CSRF (high 8.8)
- [CVE-2023-52233](https://insights.sbomify.com/CVE-2023-52233/): WordPress POST SMTP Mailer plugin <= 2.8.6 - Broken Access Control on API vulnerability (high 8.6)
- [CVE-2024-52436](https://insights.sbomify.com/CVE-2024-52436/): WordPress Post SMTP plugin <= 2.9.9 - SQL Injection vulnerability (high 7.6)
- [CVE-2025-0521](https://insights.sbomify.com/CVE-2025-0521/): Post SMTP <= 3.0.2 - Unauthenticated Stored Cross-Site Scripting (high 7.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-6621 and fix it if it is affected.

What it is: CVE-2023-6621 is a medium-severity cross-site scripting vulnerability in Unknown POST SMTP, published on 3 Jan 2024. 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-2023-6621 exists.

Affected product: Unknown POST SMTP. 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-2023-6621/ (Markdown: https://insights.sbomify.com/CVE-2023-6621/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6621
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6621
- OSV: https://osv.dev/vulnerability/CVE-2023-6621

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6621/
Summaries are generated and may contain mistakes; the official description above is the record.