CWE•Base•Draft•4 recent CVEs
CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
Description
The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.
If the DTD contains a large number of nested or recursive entities, this can lead to explosive growth of data when parsed, causing a denial of service.
Common consequences
- Availability→DoS: Resource Consumption (Other)If parsed, recursive entity references allow the attacker to expand data exponentially, quickly consuming all system resources.
Potential mitigations
- OperationIf possible, prohibit the use of DTDs or use an XML parser that limits the expansion of recursive DTD entities.
- ImplementationBefore parsing XML files with associated DTDs, scan for recursive entity declarations and do not continue parsing potentially explosive content.