How severe is CVE-2023-44390?

CVE-2023-44390 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-44390?

CVE-2023-44390 affects the following packages: HtmlSanitizer (NuGet), HtmlSanitizer (NuGet). Ecosystems affected: NuGet.

How do I fix CVE-2023-44390?

Update HtmlSanitizer to 8.0.723 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-44390 is resolved across your whole dependency graph.

How do I detect CVE-2023-44390 in my NuGet dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for HtmlSanitizer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2023-44390 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2023-44390?

O3 pinpoints whether CVE-2023-44390 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2023-44390 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-44390 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-44390?

CVE-2023-44390 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 28th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2023-44390 published, and has it been updated?

CVE-2023-44390 was published on October 5, 2023 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

.NET NuGet

CVE-2023-44390

MEDIUM

HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content

Also known asGHSA-43cp-6p3q-2pc4

Published

Oct 5, 2023

Updated

Apr 10, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk28th percentile+0.20%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

2 pkgs affected

.NETHtmlSanitizer.NETHtmlSanitizer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

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).

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`HtmlSanitizer`	all versions	8.0.723
.NETNuGet	`HtmlSanitizer`	≥ 8.1.0-beta&&< 8.1.722-beta	8.1.722-beta

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for HtmlSanitizer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update HtmlSanitizer to 8.0.723 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-44390 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-44390 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2023-44390. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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).

O3 Security · Impact-Aware SCA

Is CVE-2023-44390 in your dependencies?

O3 detects CVE-2023-44390 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works