An issue was discovered in rack-protection/lib/rack/protection/path_traversal.rb in Sinatra 2.x before 2.0.1 on Windows.

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• sinatrarb sinatra2.0.0
• sinatrarb sinatra2.0.1

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2022-45442Sinatra vulnerable to Reflected File Download attack
  35Monitor
• CVE-2022-29970Sinatra before 2.2.0 does not validate that the expanded path matches public_dir when serving static files.
  31Monitor
• CVE-2018-11627Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.
  25Monitor
• CVE-2025-61921Sinatra has ReDoS vulnerability in ETag header value generation
  10Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1const file = path.join(ROOT, req.query.name);2res.sendFile(file);

1const file = path.resolve(ROOT, req.query.name);2if (!file.startsWith(ROOT + path.sep)) {3  return res.sendStatus(400);4}5res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.