# CVE-2021-24288: AcyMailing < 7.5.0 - Unauthenticated Open Redirect

> An attacker can craft a malicious link that redirects victims to a phishing site via the unsanitized redirect parameter in the AcyMailing plugin.

- **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:** 17 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-vrm9-x4ww-qpgw

## What is CVE-2021-24288?

CVE-2021-24288 is a medium-severity vulnerability in Newsletter via SMTP, Sendinblue, Sendgrid, Mailgun - AcyMailing SMTP Newsletter, published on 17 May 2021. 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

When subscribing using AcyMailing, the 'redirect' parameter isn't properly sanitized. Turning the request from POST to GET, an attacker can craft a link containing a potentially malicious landing page and send it to the victim.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2021-24288?

It affects 1 product.


Products: Acymailing Acymailing.

## How do I fix CVE-2021-24288?

No fix has been published for CVE-2021-24288 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-24288 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-24288 exists.

Public exploit code:

- WordPress AcyMailing <7.5.0 - Open Redirect (nuclei): http/cves/2021/CVE-2021-24288.yaml

## Other vulnerabilities in Newsletter via SMTP, Sendinblue, Sendgrid, Mailgun - AcyMailing SMTP Newsletter

- [CVE-2023-28731](https://insights.sbomify.com/CVE-2023-28731/): Unauthenticated RCE affecting the AcyMailing plugin for Joomla (critical 9.8)
- [CVE-2026-94132](https://insights.sbomify.com/CVE-2026-94132/): File upload in AcyMailing Enterprise extension for Joomla (critical 9.5)
- [CVE-2026-56292](https://insights.sbomify.com/CVE-2026-56292/): Joomla Extension - acymailing.com - SQL Injection in AcyMailing extension < 10.11.1 (critical 9.2)
- [CVE-2026-94131](https://insights.sbomify.com/CVE-2026-94131/): Joomla Extension - acymailing.com - Unauthenticated arbitrary file deletion in AcyMailing Enterprise extension < 11.1.0 (high 8.3)
- [CVE-2024-7384](https://insights.sbomify.com/CVE-2024-7384/): AcyMailing <= 9.7.2 - Authenticated (Subscriber+) Arbitrary File Upload via acym_extractArchive Function (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-24288 and fix it if it is affected.

What it is: CVE-2021-24288 is a medium-severity vulnerability in Newsletter via SMTP, Sendinblue, Sendgrid, Mailgun - AcyMailing SMTP Newsletter, published on 17 May 2021. 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-2021-24288 exists.

Affected product: Newsletter via SMTP, Sendinblue, Sendgrid, Mailgun - AcyMailing SMTP Newsletter. 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-2021-24288/ (Markdown: https://insights.sbomify.com/CVE-2021-24288/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-24288
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-24288
- OSV: https://osv.dev/vulnerability/CVE-2021-24288

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-24288/
Summaries are generated and may contain mistakes; the official description above is the record.