CVE-2025-61780 (Medium) detected in rack-2.2.9.gem

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## CVE-2025-61780 - Medium Severity Vulnerability
Vulnerable Library - rack-2.2.9.gem

Rack provides a minimal, modular and adaptable interface for developing
web applications in Ruby. By wrapping HTTP requests and responses in
the simplest way possible, it unifies and distills the API for web
servers, web frameworks, and software in between (the so-called
middleware) into a single method call.

Library home page: https://rubygems.org/gems/rack-2.2.9.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /home/wss-scanner/.gem/ruby/3.2.0/cache/rack-2.2.9.gem

Dependency Hierarchy:
- rack-test-2.1.0.gem (Root Library)
- :x: **rack-2.2.9.gem** (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Rack is a modular Ruby web server interface. Prior to versions 2.2.20, 3.1.18, and 3.2.3, a possible information disclosure vulnerability existed in "Rack::Sendfile" when running behind a proxy that supports "x-sendfile" headers (such as Nginx). Specially crafted headers could cause "Rack::Sendfile" to miscommunicate with the proxy and trigger unintended internal requests, potentially bypassing proxy-level access restrictions. When "Rack::Sendfile" received untrusted "x-sendfile-type" or "x-accel-mapping" headers from a client, it would interpret them as proxy configuration directives. This could cause the middleware to send a "redirect" response to the proxy, prompting it to reissue a new internal request that was not subject to the proxy's access controls. An attacker could exploit this by setting a crafted "x-sendfile-type: x-accel-redirect" header, setting a crafted "x-accel-mapping" header, and requesting a path that qualifies for proxy-based acceleration. Attackers could bypass proxy-enforced restrictions and access internal endpoints intended to be protected (such as administrative pages). The vulnerability did not allow arbitrary file reads but could expose sensitive application routes. This issue only affected systems meeting all of the following conditions: The application used "Rack::Sendfile" with a proxy that supports "x-accel-redirect" (e.g., Nginx); the proxy did not always set or remove the "x-sendfile-type" and "x-accel-mapping" headers; and the application exposed an endpoint that returned a body responding to ".to_path". Users should upgrade to Rack versions 2.2.20, 3.1.18, or 3.2.3, which require explicit configuration to enable "x-accel-redirect". Alternatively, configure the proxy to always set or strip the header, or in Rails applications, disable sendfile completely.
Mend Note: The description of this vulnerability differs from MITRE.

Publish Date: 2025-10-10

URL: CVE-2025-61780

CVSS 3 Score Details (5.8)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Changed
- Impact Metrics:
- Confidentiality Impact: Low
- Integrity Impact: None
- Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Origin: https://github.com/advisories/GHSA-r657-rxjc-j557

Release Date: 2025-10-10

Fix Resolution: rack - 3.1.18,rack - 3.2.3,rack - 2.2.20

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Start with /Gemfile.lock, where rack-2.2.9 is recorded as a dependency of rack-test-2.1.0. Update Rack to a fixed release listed in the issue, then verify that dependency resolution succeeds and the lockfile no longer contains the vulnerable version.

Written by the indexing model from the issue text.