Description
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.
INFO
Published Date :
2026-04-02T16:43:08.762Z
Last Modified :
2026-04-02T16:43:08.762Z
Source :
GitHub_M
AFFECTED PRODUCTS
The following products are affected by CVE-2026-34831 vulnerability.
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REFERENCES
Here, you will find a curated list of external links that provide in-depth information to CVE-2026-34831.
