Horizon Alert
Summary of the vulnerability and why it matters
A security vulnerability in Undertow could allow attackers to bypass security controls by exploiting discrepancies in how header names are interpreted between Undertow and upstream proxies, potentially leading to unauthorized access.
- Attackers can smuggle requests to bypass security.
- Matters for external-facing web services and applications.
- Confirm relevance and exposure for your environment.
Attack Path
How an attacker could exploit the issue
An attacker can exploit this vulnerability by sending specially crafted requests to a system using Undertow. The attacker crafts requests where header names are interpreted differently by Undertow than by any upstream proxy. This difference in interpretation allows the attacker to smuggle malicious requests past security controls.
- Requires network access.
- Crafted HTTP requests trigger parsing differences.
- Bypasses security and accesses unauthorized resources.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow attackers to bypass security controls by exploiting differences in how Undertow and upstream proxies interpret HTTP header names. This may lead to unauthorized access to resources or sensitive information.
- Sensitive system data and resources.
- Maliciously crafted HTTP requests.
- Unauthorized access to data and resources.
Operational Fix
Recommended remediation, mitigation, and detection steps
Teams responsible for application platforms, web servers, and potentially network security controls should address this vulnerability. The first practical step is to identify all instances of the affected Undertow component, confirm their exposure and business criticality, and then engage the respective owners to plan remediation.
- Application owners and platform teams.
- Verify external exposure and criticality.
- Plan coordinated remediation.
