CVE-2023-51652 Information

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.

Reference

https://github.com/spassarop/antisamy-dotnet/security/advisories/GHSA-8x6f-956f-q43w https://github.com/spassarop/antisamy-dotnet/commit/7e500daef6ad9c10e97c68feab78f4cb6e3083c6 https://github.com/spassarop/antisamy-dotnet/commit/8117911933e75a25cd0054ef017577486338444a