Horizon Alert
Summary of the vulnerability and why it matters
This advisory addresses a critical vulnerability identified in the APR-util library. The issue involves a stack recursion flaw that can be exploited when parsing XML from untrusted sources using a specific function. While the library itself is a foundational component, its use in processing external XML data could pose a risk depending on how it's implemented within our systems.
- XML parsing flaw in a common library.
- Matters if we process external XML data.
- Confirm relevance and exposure to untrusted XML.
Attack Path
How an attacker could exploit the issue
An attacker can trigger this vulnerability by sending specially crafted XML data to an application that parses it. This XML data would exploit a flaw in the `apr_xml_quote_elem()` function, leading to a stack recursion issue. If an application consumes XML from untrusted sources and uses this function, an attacker could potentially cause a denial-of-service condition or execute arbitrary code.
- Requires network access to an XML parsing function.
- Triggered by untrusted XML input.
- Risk of denial-of-service or code execution.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could impact applications that parse untrusted XML data using a specific function. When this function is called with maliciously crafted XML, it may lead to a stack recursion attack, potentially causing the application to crash or become unresponsive. The advisory does not indicate risks to user data or PII.
- Service stability and availability.
- Untrusted XML parsing triggers recursion.
- Application crash or unresponsiveness.
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability impacts applications that use APR-util to parse XML from untrusted sources. Ownership typically lies with the application owner or development team responsible for the affected software, in coordination with infrastructure or platform teams for deployment and patching. The first step is to identify all instances of the affected library, confirm if they process external XML, and then plan remediation based on the risk of exposure.
- Application owners should own the issue.
- Verify XML parsing and untrusted input.
- Plan upgrade or isolate vulnerable components.
