# Cwe 643 Xpath Injection

> 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.

- Skill: `developerscoffee/cwe-643-xpath-injection` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-643-xpath-injection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-643-xpath-injection/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- License: MIT
- Author: DevelopersCoffee (https://skillmd.com/u/developerscoffee)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/developerscoffee/cwe-643-xpath-injection

---


# CWE-643 XPath Injection

## Description

XPath Injection

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


**OWASP Category**: A03:2021 – Injection


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// 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




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// 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




---

## Detection Pattern

Look for these patterns in your codebase:


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



---

## 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


---

## Key Imports

```java

import javax.xml.xpath.XPath;

import javax.xml.xpath.XPathVariableResolver;

import javax.xml.namespace.QName;

```

---

## 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


---

## Trigger Examples

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

---

## Common Vulnerable Locations

| Layer | Files | Patterns |
|-------|-------|----------|

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

| Service | `*Service.java` | Business logic |

| Repository | `*Repository.java` | Data access |


---

## References


- [CWE-643: XPath Injection](https://cwe.mitre.org/data/definitions/643.html)


---

**Source**: Generated by [Java CWE Security Skills Generator](https://github.com/DevelopersCoffee/java-cwe-security-skills)
**Last Updated**: 2026-03-07