# CVE-2021-42663: Cross-site scripting in n/a

> Attackers can inject HTML into the event booking system to alter website visibility and display malicious content to users.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/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:** 5 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-948r-pr54-gh74

## What is CVE-2021-42663?

CVE-2021-42663 is a medium-severity cross-site scripting vulnerability in n/a, published on 5 Nov 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

An HTML injection vulnerability exists in Sourcecodester Online Event Booking and Reservation System in PHP/MySQL via the msg parameter to /event-management/index.php. An attacker can leverage this vulnerability in order to change the visibility of the website. Once the target user clicks on a given link he will display the content of the HTML code of the attacker's choice.

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

## Which versions are affected by CVE-2021-42663?

It affects 1 product.


Products: Online Event Booking and Reservation System Project Online Event Booking and Reservation System.

## How do I fix CVE-2021-42663?

No fix has been published for CVE-2021-42663 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-42663 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-42663 exists.

Public exploit code:

- CVE-2021-42663 - HTML Injection vulnerability in the Online event booking and reservation system.  (github_poc): https://github.com/0xDeku/CVE-2021-42663
- Sourcecodester Online Event Booking and Reservation System 2.3.0 - Cross-Site Scripting (nuclei): http/cves/2021/CVE-2021-42663.yaml

## Other vulnerabilities in n/a

- [CVE-2021-42667](https://insights.sbomify.com/CVE-2021-42667/): SQL injection in n/a (critical 9.8)
- [CVE-2021-42662](https://insights.sbomify.com/CVE-2021-42662/): Cross-site scripting in n/a (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42663 and fix it if it is affected.

What it is: CVE-2021-42663 is a medium-severity cross-site scripting vulnerability in n/a, published on 5 Nov 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-2021-42663 exists.

Affected product: n/a. 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-2021-42663/ (Markdown: https://insights.sbomify.com/CVE-2021-42663/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42663
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42663
- OSV: https://osv.dev/vulnerability/CVE-2021-42663

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42663/
Summaries are generated and may contain mistakes; the official description above is the record.