Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-112 Base Draft
Missing XML Validation
This vulnerability occurs when an application processes XML data from an untrusted source without first validating its structure and content against a defined schema.
Definition
What is CWE-112?
This vulnerability occurs when an application processes XML data from an untrusted source without first validating its structure and content against a defined schema.
When you accept XML without schema validation, you're trusting external data to match your code's expectations. Attackers exploit this gap by sending malformed, oversized, or maliciously crafted XML documents that can trigger parsing errors, consume excessive resources, or enable injection attacks. This fundamentally breaks the security assumption that input will be reasonable and well-formed.
Consistently validating XML against a strict DTD or XML Schema is a critical first line of defense. While SAST tools can detect missing validation patterns, Plexicus uses AI to analyze your code flow and suggest precise fixes—like implementing schema validation libraries or hardening parser configurations—saving hours of manual security review and helping prevent this common oversight across your entire application portfolio.
Real-world impact
Real-world CVEs caused by CWE-112
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
The following code loads and parses an XML file.
- 2
The XML file is loaded without validating it against a known XML Schema or DTD.
- 3
The following code creates a DocumentBuilder object to be used in building an XML document.
- 4
The DocumentBuilder object does not validate an XML document against a schema, making it possible to create an invalid XML document.
Vulnerable code example
Vulnerable Java
The following code loads and parses an XML file.
```
// Read DOM*
try {
```
...
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating( false );
....
c_dom = factory.newDocumentBuilder().parse( xmlFile );
} catch(Exception ex) {
...
} Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-112
- Architecture and Design Always validate XML input against a known XML Schema or DTD. It is not possible for an XML parser to validate all aspects of a document's content because a parser cannot understand the complete semantics of the data. However, a parser can do a complete and thorough job of checking the document's structure and therefore guarantee to the code that processes the document that the content is well-formed.
Detection signals
How to detect CWE-112
Plexicus auto-detects CWE-112 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-112?
How serious is CWE-112?
What languages or platforms are affected by CWE-112?
How can I prevent CWE-112?
How does Plexicus detect and fix CWE-112?
Where can I learn more about CWE-112?
Frequently asked questions
What is CWE-112?
This vulnerability occurs when an application processes XML data from an untrusted source without first validating its structure and content against a defined schema.
How serious is CWE-112?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-112?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-112?
Always validate XML input against a known XML Schema or DTD. It is not possible for an XML parser to validate all aspects of a document's content because a parser cannot understand the complete semantics of the data. However, a parser can do a complete and thorough job of checking the document's structure and therefore guarantee to the code that processes the document that the content is well-formed.
How does Plexicus detect and fix CWE-112?
Plexicus's SAST engine matches the data-flow signature for CWE-112 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-112?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/112.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Resources
Further reading
- MITRE — official CWE-112 https://cwe.mitre.org/data/definitions/112.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
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