CWE-135
Incorrect Calculation of Multi-Byte String Length
BaseDraft
Description
The product does not correctly calculate the length of strings that can contain wide or multi-byte characters.
Hierarchy (View 1000)
Parents
Children
none
CVEs mapped to this weakness (1)
| CVE | Sev | Risk | CVSS | EPSS | KEV | Published | Description |
|---|---|---|---|---|---|---|---|
| CVE-2026-34831 | Med | 0.31 | 4.8 | 0.00 | Apr 2, 2026 | Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Files#fail sets the Content-Length response header using String#size instead of String#bytesize. When the response body contains multibyte UTF-8 characters, the declared Content-Length is smaller than the number of bytes actually sent on the wire. Because Rack::Files reflects the requested path in 404 responses, an attacker can trigger this mismatch by requesting a non-existent path containing percent-encoded UTF-8 characters. This results in incorrect HTTP response framing and may cause response desynchronization in deployments that rely on the incorrect Content-Length value. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6. |