CVE-2019-10184 in Undertow
Summary
by MITRE
undertow before version 2.0.23.Final is vulnerable to an information leak issue. Web apps may have their directory structures predicted through requests without trailing slashes via the api.
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Analysis
by VulDB Data Team • 08/24/2025
The vulnerability identified as CVE-2019-10184 affects the undertow web server component prior to version 2.0.23.Final, representing a significant information disclosure weakness that exposes directory structures to remote attackers. This flaw specifically manifests when web applications process requests lacking trailing slashes in their paths, creating predictable patterns that reveal internal directory layouts and application architecture. The issue stems from undertow's handling of URL normalization and path resolution mechanisms, where the server fails to properly sanitize or canonicalize requests that do not include trailing slashes, allowing malicious actors to infer the underlying file system structure of deployed applications.
The technical implementation of this vulnerability resides in undertow's request processing pipeline where path traversal logic does not adequately account for the absence of trailing slashes in HTTP requests. When a client submits a request without a trailing slash, the web server's internal path resolution algorithms may inadvertently expose directory listings or reveal structural information about the application's file hierarchy. This behavior creates a predictable information leak pattern that attackers can exploit systematically to map application directories and identify potential attack vectors. The vulnerability operates at the application layer and can be classified under CWE-200, which addresses information exposure, while also aligning with ATT&CK technique T1213.002 for data from information repositories.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with critical reconnaissance data that can inform subsequent exploitation attempts. Once directory structures are revealed, attackers can identify sensitive files, configuration data, or application components that may contain further vulnerabilities. This information leak creates a foundation for more sophisticated attacks including directory traversal, path manipulation, and potentially privilege escalation within the application environment. The vulnerability particularly affects web applications deployed using undertow as their primary web server component, making it a significant concern for organizations relying on this technology stack.
Organizations should implement immediate mitigations including upgrading to undertow version 2.0.23.Final or later, which contains the necessary patches to address the information leak behavior. Additionally, security teams should review their web application configurations to ensure proper URL handling and path normalization. Network-level protections such as web application firewalls can provide additional defense in depth, while application-level controls should enforce consistent URL formatting and implement proper input validation. The fix addresses the root cause by implementing stricter path canonicalization routines that ensure consistent handling of requests regardless of trailing slash presence, thereby eliminating the predictable information disclosure patterns that enabled this vulnerability.