CVE-2026-22860

Rack::Directory’s path check used a string prefix match on the expanded path. A request like /../root_example/ can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root.

Details

In directory.rb, File.expand_path(File.join(root, path_info)).start_with?(root) does not enforce a path boundary. If the server root is /var/www/root, a path like /var/www/root_backup passes the check because it shares the same prefix, so Rack::Directory will list that directory also.

Mitigation

• Update to a patched version of Rack that correctly checks the root prefix.
• Don't name directories with the same prefix as one which is exposed via Rack::Directory.

Information disclosure via directory listing outside the configured root when Rack::Directory is exposed to untrusted clients and a directory shares the root prefix (e.g., public2, www_backup).

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-22860 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.2.22, 3.1.20, 3.2.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-22860? CVE-2026-22860 is a high-severity path traversal vulnerability in rack (rubygems), affecting versions < 2.2.22. It is fixed in 2.2.22, 3.1.20, 3.2.5. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-22860? CVE-2026-22860 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of rack are affected by CVE-2026-22860? rack (rubygems) versions < 2.2.22 is affected.
4. Is there a fix for CVE-2026-22860? Yes. CVE-2026-22860 is fixed in 2.2.22, 3.1.20, 3.2.5. Upgrade to this version or later.
5. Is CVE-2026-22860 exploitable, and should I be worried? Whether CVE-2026-22860 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-22860 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-22860?
   • Upgrade rack to 2.2.22 or later
   • Upgrade rack to 3.1.20 or later
   • Upgrade rack to 3.2.5 or later