# CVE-2021-24535: Light Messages <= 1.0 - CSRF to Stored XSS

> An attacker can trick an admin into updating settings to inject a stored XSS payload, potentially leading to code execution or 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:** 16 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6g8x-82fh-m598

## What is CVE-2021-24535?

CVE-2021-24535 is a medium-severity cross-site scripting vulnerability in Unknown Light Messages, published on 16 Aug 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

The Light Messages WordPress plugin through 1.0 is lacking CSRF check when updating it's settings, and is not sanitising its Message Content in them (even with the unfiltered_html disallowed). As a result, an attacker could make a logged in admin update the settings to arbitrary values, and set a Cross-Site Scripting payload in the Message Content. Depending on the options set, the XSS payload can be triggered either in the backend only (in the plugin's settings), or both frontend and backend.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2021-24535?

It affects 1 product.


Products: Light Messages Project Light Messages.

## How do I fix CVE-2021-24535?

No fix has been published for CVE-2021-24535 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-24535 being exploited?

There is no known exploitation of CVE-2021-24535 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-24535 and fix it if it is affected.

What it is: CVE-2021-24535 is a medium-severity cross-site scripting vulnerability in Unknown Light Messages, published on 16 Aug 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: There is no known exploitation of CVE-2021-24535 in the wild and no public exploit code.

Affected product: Unknown Light Messages. 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-2021-24535/ (Markdown: https://insights.sbomify.com/CVE-2021-24535/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-24535
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-24535
- OSV: https://osv.dev/vulnerability/CVE-2021-24535

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-24535/
Summaries are generated and may contain mistakes; the official description above is the record.