Handlebars.java before 4.5.5 allows directory traversal

Why it is Amber

• CVSS 7.5 high
• Remotely exploitable without logging in

References

• https://github.com/jknack/handlebars.java/commit/f6ae3979917d05bef07f00befb4013ef00503660
• https://github.com/jknack/handlebars.java/releases/tag/v4.5.5
• https://github.com/jknack/handlebars.java/security/advisories/GHSA-pvrx-3g7m-fpgv
• https://github.com/jknack/handlebars.java/security/advisories/GHSA-pvrx-3g7m-fpgv

Original description

Handlebars.java before 4.5.5 allows directory traversal. In handlebars-springmvc 4.5.3 and 4.5.4, the path-containment fix for CVE-2026-63490 validates template locations as raw percent-encoded strings, whereas the template file is opened through a URL handler that percent-decodes the path. In a Spring MVC application with a file: template prefix and a request-derived view name, a percent-encoded traversal such as %2e%2e/ bypasses both the view-resolver check and the loader-side containment and reads files outside the configured template base directory.