Vulnerability · Published Jan 2, 2024 · Assigned by GitHub_M
CVE-2023-51652OWASP.AntiSamy mXSS when preserving comments
Medium 6.1
In plain English
A medium-severity cross-site scripting in antisamy-dotnet from spassarop. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| NuGet | owasp.antisamy | 1.2.0 | GHSA-8x6f-956f-q43w |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| spassarop | antisamy-dotnet | < 1.2.0 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
References
- https://github.com/spassarop/antisamy-dotnet/security/advisories/GHSA-8x6f-956f-q43w x_refsource_CONFIRM
- https://github.com/spassarop/antisamy-dotnet/commit/7e500daef6ad9c10e97c68feab78f4cb6e3083c6 x_refsource_MISC
- https://github.com/spassarop/antisamy-dotnet/commit/8117911933e75a25cd0054ef017577486338444a x_refsource_MISC