# CVE-2023-44390: HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content

> Attackers can bypass sanitization and inject JavaScript if foreign content like SVG or Math is explicitly allowed in the configuration.

- **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:** Yes
- **Published:** 5 Oct 2023
- **Updated:** 19 Sep 2024
- **Also known as:** GHSA-43cp-6p3q-2pc4

## What is CVE-2023-44390?

CVE-2023-44390 is a medium-severity cross-site scripting vulnerability in mganss HtmlSanitizer, published on 5 Oct 2023. 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

HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. The vulnerability occurs in configurations where foreign content is allowed, i.e. either `svg` or `math` are in the list of allowed elements. In the case an application sanitizes user input with a vulnerable configuration, an attacker could bypass the sanitization and inject arbitrary HTML, including JavaScript code. Note that in the default configuration the vulnerability is not present. The vulnerability has been fixed in versions 8.0.723 and 8.1.722-beta (preview version).

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

## Which versions are affected by CVE-2023-44390?

4 open source packages ship an affected version, including HtmlSanitizer. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `HtmlSanitizer` | NuGet | All versions | 8.0.723 |
| `HtmlSanitizer` | NuGet | All versions | 8.0.723 |
| `HtmlSanitizer` | NuGet | From 8.1.0-beta | 8.1.722-beta |
| `HtmlSanitizer` | NuGet | From 8.1.0-beta | 8.1.722-beta |

Products: Htmlsanitizer Project Htmlsanitizer.

## How do I fix CVE-2023-44390?

Upgrade HtmlSanitizer to a fixed version for your release line: 8.0.723 or 8.1.722-beta.

## Is CVE-2023-44390 being exploited?

There is no known exploitation of CVE-2023-44390 in the wild and no public exploit code.

## Other vulnerabilities in mganss HtmlSanitizer

- [CVE-2026-25543](https://insights.sbomify.com/CVE-2026-25543/): HtmlSanitizer has a bypass via template tag (medium 6.3)
- [CVE-2020-26293](https://insights.sbomify.com/CVE-2020-26293/): Possible XSS bypass if style tag is allowed (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-44390 and fix it if it is affected.

What it is: CVE-2023-44390 is a medium-severity cross-site scripting vulnerability in mganss HtmlSanitizer, published on 5 Oct 2023. 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-2023-44390 in the wild and no public exploit code.

Affected packages and fixed versions:
- HtmlSanitizer (NuGet): affected all versions; fixed in 8.0.723
- HtmlSanitizer (NuGet): affected all versions; fixed in 8.0.723
- HtmlSanitizer (NuGet): affected from 8.1.0-beta; fixed in 8.1.722-beta
- HtmlSanitizer (NuGet): affected from 8.1.0-beta; fixed in 8.1.722-beta

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-2023-44390/ (Markdown: https://insights.sbomify.com/CVE-2023-44390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-44390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-44390
- OSV: https://osv.dev/vulnerability/CVE-2023-44390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-44390/
Summaries are generated and may contain mistakes; the official description above is the record.