Horizon Alert
Summary of the vulnerability and why it matters
This advisory describes vulnerabilities in the Nokogiri software library, which is used for processing XML and HTML. The issues could allow for denial of service or potentially the execution of malicious code if the software processes specially crafted data. The main concern is confirming if our organization uses this library and is therefore potentially exposed.
- Vulnerabilities exist in XML processing software.
- Understand if and how our systems use this library.
- Confirm relevance and assess potential exposure.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this vulnerability by sending specially crafted DTD or XSD data to an application that uses a vulnerable version of the Nokogiri library. This malicious input targets how the library handles validation errors and schema processing, potentially leading to unexpected behavior. If successful, an attacker could cause the application to crash, preventing legitimate users from accessing it, or, in some scenarios, execute their own code within the context of the application.
- Requires an application using vulnerable Nokogiri.
- Triggered by providing malicious DTD or XSD.
- Risk of denial of service or code execution.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, applications processing XML data with long QName prefixes in DTDs or untrusted XML Schemas could experience crashes or unexpected behavior due to stack buffer overflows and use-after-free vulnerabilities.
- Application processing of DTDs or XSD files.
- Malicious DTD or untrusted XSD files provided.
- Denial of service or potential code execution.
Operational Fix
Recommended remediation, mitigation, and detection steps
Teams responsible for applications embedding Nokogiri should investigate its usage, focusing on any instances processing untrusted DTD or XSD files. The initial step involves an inventory of where Nokogiri is deployed, assessing exposure through application context, and identifying the accountable application owner to prioritize remediation based on observed risk and potential business impact.
- Application owners must manage this vulnerability.
- Verify untrusted DTD or XSD processing.
- Plan remediation based on application risk.
