cwe-643-xpath-injection

name	cwe-643-xpath-injection
description	Use this skill when you need to remediate CWE-643 (XPath Injection) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing xpath injection issues.
version	1.0.0
license	MIT
tags	["security","java","cwe-643","remediation","sast","xpath-injection","xml","injection"]

CWE-643 XPath Injection

Description

XPath Injection

Reference: https://cwe.mitre.org/data/definitions/643.html

OWASP Category: A03:2021 – Injection

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Vulnerable Pattern

❌ Example 1: Vulnerable Pattern

// VULNERABLE: String concatenation in XPath
String username = request.getParameter("user");
String xpath = "//users/user[name='" + username + "']/password";
XPathExpression expr = xPath.compile(xpath);
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

Why it's vulnerable: This pattern is vulnerable to XPath Injection

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Deterministic Fix

✅ Secure Implementation: Secure Implementation

// SECURE: Use XPath variables (parameterized)
String username = request.getParameter("user");

// Create a variable resolver
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setXPathVariableResolver(new XPathVariableResolver() {
    @Override
    public Object resolveVariable(QName variableName) {
        if ("username".equals(variableName.getLocalPart())) {
            return username;  // Safely bound
        }
        return null;
    }
});

// Use variable reference instead of concatenation
String xpath = "//users/user[name=$username]/password";
XPathExpression expr = xPath.compile(xpath);
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

Why it's secure: Implements proper protection against XPath Injection

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Detection Pattern

Look for these patterns in your codebase:

# Find XPath with concatenation
grep -rn "xPath.compile\|XPathExpression" --include="*.java" | grep "\\+"

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Remediation Steps

1. Use XPathVariableResolver for parameterized queries

2. Reference variables with $varname syntax

3. Validate input against expected patterns

4. Consider using typed XML libraries instead of XPath

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Key Imports

import javax.xml.xpath.XPath;

import javax.xml.xpath.XPathVariableResolver;

import javax.xml.namespace.QName;

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Verification

After remediation:

• Run SAST scanner to confirm vulnerability is resolved

• Review all instances of the vulnerable pattern

• Add unit tests that verify the secure implementation

• Check for similar patterns in related code

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Trigger Examples

Fix CWE-643 vulnerability
Resolve XPath Injection issue
Secure this Java code against xpath injection
SAST reports CWE-643

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Common Vulnerable Locations

Layer	Files	Patterns

| Controller | *Controller.java | User input handling |

| Service | *Service.java | Business logic |

| Repository | *Repository.java | Data access |

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References

• CWE-643: XPath Injection

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Source: Generated by Java CWE Security Skills Generator Last Updated: 2026-03-07