Failure to Sanitize Data within XPath Expressions ('XPath injection')
Weakness ID: 643 (Weakness Base)Status: Incomplete
+ Description

Description Summary

The software uses external input to dynamically construct an XPath expression used to retrieve data from an XML database, but it does not sufficiently sanitize that input. This allows an attacker to control the structure of the query.

Extended Description

The net effect is that the attacker will have control over the information selected from the XML database and may use that ability to control application flow, modify logic, retrieve unauthorized data, or bypass important checks (e.g. authentication).

+ Time of Introduction
  • Implementation
+ Applicable Platforms



+ Common Consequences

Controlling application flow (e.g. bypassing authentication)


Information disclosure

+ Likelihood of Exploit


+ Enabling Factors for Exploitation

XPath queries are constructed dynamically using user supplied input

The application does not perform sufficient validation or sanitization of user supplied input

+ Demonstrative Examples

Example 1

Consider the following simple XML document that stores authentication information and a snippet of Java code that uses XPath query to retrieve authentication information:

Example Language: XML 

The Java code used to retrieve the home directory based on the provided credentials is:

(Bad Code)
Example Language: Java 
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression xlogin = xpath.compile("//users/user[login/text()='" + login.getUserName() + "' and password/text() = '" + login.getPassword() + "']/home_dir/text()");
Document d = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File("db.xml"));
String homedir = xlogin.evaluate(d);

Assume that user "john" wishes to leverage XPath Injection and login without a valid password. By providing a username "john" and password "' or ''='" the XPath expression now becomes

//users/user[login/text()='john' or ''='' and password/text() = '' or ''='']/home_dir/text()

which, of course, lets user "john" login without a valid password, thus bypassing authentication.

+ Potential Mitigations

Use parameterized XPath queries (e.g. using XQuery). This will help ensure separation between data plane and control plane.

Properly validate user input. Reject data where appropriate, filter where appropriate and escape where appropriate. Make sure input that will be used in XPath queries is safe in that context.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness BaseWeakness Base91XML Injection (aka Blind XPath Injection)
Development Concepts (primary)699
Research Concepts (primary)1000
+ Relationship Notes

This weakness is similar to other weaknesses that enable injection style attacks, such as SQL injection, command injection and LDAP injection. The main difference is that the target of attack here is the XML database.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
WASC39XPath Injection
+ References
Web Application Security Consortium. "XPath Injection". <>.
+ Content History
Submission DateSubmitterOrganizationSource
2008-01-30Evgeny LebanidzeCigitalExternal Submission
Modification DateModifierOrganizationSource
2008-09-08CWE Content TeamMITREInternal
updated Common Consequences, Relationships
2008-10-14CWE Content TeamMITREInternal
updated Description, Name, References, Relationship Notes
2009-03-10CWE Content TeamMITREInternal
updated Demonstrative Examples
2009-05-27CWE Content TeamMITREInternal
updated Name
2009-10-29CWE Content TeamMITREInternal
updated Common Consequences
Previous Entry Names
Change DatePrevious Entry Name
2008-10-14Unsafe Treatment of XPath Input
2009-05-27Failure to Sanitize Data within XPath Expressions (aka 'XPath injection')