Listen to this Post
The vulnerability in libxmljs version 1.0.11 arises from improper handling of internal properties when parsing specially crafted XML documents. Specifically, accessing the internal _ref property on entity_ref and entity_decl nodes triggers a segmentation fault due to a null pointer dereference or invalid memory access. This occurs because the C++ bindings for libxml2 expose the _ref property to JavaScript without proper validation. When a malicious XML document containing engineered entity references or declarations is parsed, the _ref property points to an uninitialized or freed memory location. The libxml2 library underlying libxmljs fails to safely manage these entity nodes, leading to a crash when the property is accessed. This segmentation fault directly causes a denial-of-service, as the application using libxmljs terminates abruptly. The vulnerability can be exploited remotely if libxmljs is used in a server-side application to process XML input, such as in web services or APIs. An attacker can submit a crafted XML payload that, when parsed, forces the access of _ref on vulnerable nodes, crashing the process and disrupting service. The issue is rooted in the native code integration where JavaScript objects wrap libxml2 structures, and the _ref property is not guarded against invalid states. This allows a simple XML file with nested entity references or malformed declarations to trigger the fault, requiring no authentication or user interaction. The crash is immediate upon property access, making it reliable for DoS attacks. The vulnerability is particularly critical in environments where libxmljs is used for real-time XML processing, as it can lead to sustained downtime. Mitigation involves avoiding the use of the _ref property or upgrading to a patched version once available.
Platform: libxmljs
Version: 1.0.11
Vulnerability: Segmentation Fault DoS
Severity: High
date: Dec 26 2025
Prediction: Patch Jan 2026
What Undercode Say:
Analytics
Bash commands to check version and test vulnerability:
npm list libxmljs
node -e "const libxmljs = require('libxmljs'); console.log('Version:', libxmljs.version);"
Code snippet to reproduce crash (malicious XML parsing):
const libxmljs = require('libxmljs');
const xml = <code><!DOCTYPE test [ <!ENTITY x "crafted"> ]><test>&x;</test></code>;
const doc = libxmljs.parseXml(xml);
const nodes = doc.find('//entity_ref | //entity_decl');
nodes.forEach(node => {
try { console.log(node._ref); } catch(e) { console.error('Crash induced'); }
});
how Exploit:
Craft XML with entity references/declarations. Submit to server using libxmljs for parsing. Trigger _ref access via code, causing segmentation fault and DoS.
Protection from this CVE Impact:
Upgrade libxmljs when patch released. Avoid using _ref property. Input validation for XML. Impact: Application crash, denial-of-service, potential system instability.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
