CVE-2023-51652 OWASP.AntiSamy mXSS when preserving comments
Attackers can execute arbitrary scripts via mutation XSS in OWASP AntiSamy .NET when comment preservation is enabled.
- 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
What is CVE-2023-51652?
CVE-2023-51652 is a medium-severity cross-site scripting vulnerability in spassarop antisamy-dotnet, published on 2 Jan 2024. 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
OWASP AntiSamy .NET is a library for performing cleansing of HTML coming from untrusted sources. Prior to version 1.2.0, there is a potential for a mutation cross-site scripting (mXSS) vulnerability in AntiSamy caused by flawed parsing of the HTML being sanitized. To be subject to this vulnerability the `preserveComments` directive must be enabled in your policy file and also allow for certain tags at the same time. As a result, certain crafty inputs can result in elements in comment tags being interpreted as executable when using AntiSamy's sanitized output. This is patched in OWASP AntiSamy .NET 1.2.0 and later. See important remediation details in the reference given below. As a workaround, manually edit the AntiSamy policy file (e.g., antisamy.xml) by deleting the `preserveComments` directive or setting its value to `false`, if present. Also it would be useful to make AntiSamy remove the `noscript` tag by adding a line described in the GitHub Security Advisory to the tag definitions under the `<tagrules>` node, or deleting it entirely if present. As the previously mentioned policy settings are preconditions for the mXSS attack to work, changing them as recommended should be sufficient to protect you against this vulnerability when using a vulnerable version of this library. However, the existing bug would still be present in AntiSamy or its parser dependency (HtmlAgilityPack). The safety of this workaround relies on configurations that may change in the future and don't address the root cause of the vulnerability. As such, it is strongly recommended to upgrade to a fixed version of AntiSamy.
Weakness: CWE-79
Which versions are affected by CVE-2023-51652?
2 open source packages ship an affected version, including OWASP.AntiSamy. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
OWASP.AntiSamy NuGet | All versions | 1.2.0 |
OWASP.AntiSamy NuGet | All versions | 1.2.0 |
Products include Spassarop Owasp Antisamy .Net.
How do I fix CVE-2023-51652?
Upgrade OWASP.AntiSamy to 1.2.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2023-51652 being exploited?
There is no known exploitation of CVE-2023-51652 in the wild and no public exploit code.
Sources
Also known as GHSA-8x6f-956f-q43w.