Improper Handling of Length Parameter Inconsistency Affecting ruby-rack package, versions <2.2.7-1ubuntu0.7


Severity

Recommended
0.0
medium
0
10

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.15% (4th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-UBUNTU2404-RUBYRACK-15926902
  • published16 Apr 2026
  • disclosed2 Apr 2026

Introduced: 2 Apr 2026

CVE-2026-34831  (opens in a new tab)
CWE-130  (opens in a new tab)
CWE-135  (opens in a new tab)

How to fix?

Upgrade Ubuntu:24.04 ruby-rack to version 2.2.7-1ubuntu0.7 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ruby-rack package and not the ruby-rack package as distributed by Ubuntu. See How to fix? for Ubuntu:24.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1