CVE-2026-114370: Undertow: undertow: pathresourcemanager safepaths check allows sibling-directory symlink traversal
A flaw was found in the PathResourceManager component of the Undertow web server. This component is responsible for serving static files from the file system. The issue occurs because the mechanism used to verify if a symbolic link points to a safe location only checks if the target path starts with a specific string, without ensuring it matches a full directory name. This could allow an attacker to access files in a sibling directory if that directorys name starts with the same characters as an authorized safe directory.
Affected Software
Event History
Frequently Asked Questions
Which Undertow deployments are exposed?
Deployments using PathResourceManager to serve static files from the file system may be exposed when symbolic links are evaluated against configured safe locations. The issue is relevant where a sibling directory name begins with the same characters as an authorized safe directory.
What must an attacker be able to do to exploit this issue?
An attacker must be able to make network requests to the affected Undertow server and reach a path that causes the unsafe symbolic-link validation. Exploitation is rated high complexity and does not require privileges or user interaction.
What is the potential impact?
An attacker could access files in a sibling directory that should not be permitted by the safe-path restriction. The reported impact is limited to confidentiality; integrity and availability are not affected.