mXSS in AntiSamy
Date: 2023-10
Affected: maven/org.owasp.antisamy:antisamy
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2023-43643
CWE: CWE-79
CVSS: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

# Impact There is a potential for a mutation XSS (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. # Patches Patched in AntiSamy 1.7.4 and later. See important remediation details in the reference given below. # Workarounds If you cannot upgrade to a fixed version of the library, the following mitigation can be applied until you can upgrade: Manually edit your 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 this in your tag definitions under the `<tagrules>` node (or deleting it entirely if present): ```xml <tag name="noscript" action="remove"/> ``` 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 (neko-htmlunit). The safety of this workaround relies on configurations that may change in the future and don't address


Mitigations:

Architectural layers (MAESTRO):