CVE-2023-43643 — antisamy
MEDIUMCVE-2023-43643 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.owasp.antisamy:antisamy. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.owasp.antisamy:antisamy — see the affected versions and patch details below.
mXSS in AntiSamy
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-43643.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.owasp.antisamy:antisamyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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):
<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 the root cause of the vulnerability. As such, it is strongly recommended to upgrade to a fixed version of AntiSamy.
For more information
If you have any questions or comments about this advisory:
Email one of the project co-leaders, listed on the OWASP AntiSamy project page, under "Leaders".
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.owasp.antisamy:antisamy | all versions | 1.7.4org.owasp.antisamy:antisamy:1.7.4 |
Affected Products
antisamyantisamy_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.owasp.antisamy:antisamy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.owasp.antisamy:antisamy to 1.7.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-43643 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2023-43643 in your dependencies?
Find it across Maven, including transitive dependencies.