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The Mechanize Ruby library contains multiple logic flaws in its HTTP redirect and header management implementation within lib/mechanize/http/agent.rb. Specifically, Mechanizerequest_headers= unconditionally copies default request headers onto every subsequent request without checking if a cross-host redirect has occurred. Furthermore, the redirect strip logic previously failed to evaluate other sensitive credential headers like Proxy-Authorization and Cookie2. When an automated script or application triggers an HTTP redirect leading to an untrusted external host via open redirects, DNS rebinding, or machine-in-the-middle vectors, these protected headers leak automatically to the attacker. Consequently, threat actors can harvest sensitive authorization bearer tokens and session cookies, resulting in unauthorized information disclosure without affecting service integrity or availability.
DailyCVE Form:
Platform: Ruby Mechanize
Version: Prior to 2.14.1
Vulnerability : Information Disclosure
Severity: Medium
date: 2026-10-08
Prediction: Already Patched
What Undercode Say:
To verify or inspect the header transmission mechanics or test your ruby environment for header persistence across redirects, you can review internal transport states or execute debug inspections via bash and ruby commands:
gem list mechanize ruby -r mechanize -e "p Mechanize::HTTP::Agent::CREDENTIAL_HEADERS"
agent = Mechanize.new
agent.request_headers = { 'Authorization' => 'Bearer secret' }
agent.get('https://example.test/redirects-to-attacker')
How Exploit: (Educational Purposes!)
An attacker establishes an open redirect endpoint or injects a redirect target via DNS rebinding or man-in-the-middle positioning. When the victim agent requests a benign resource that responds with a redirection to the attacker’s server, Mechanize re-applies caller-supplied headers like Authorization from agent.request_headers= or per-request arguments. The target server captures the sensitive bearer tokens or cookies instantly on the redirected request chain.
Protection: from this CVE
Upgrade the mechanize gem to version 2.14.1 or later where cross-origin redirects automatically strip sensitive tokens. Alternatively, avoid using global request headers for credentials, pass authentication parameters per-request explicitly only to trusted hosts, or disable automatic redirection handling by setting redirect_ok to false.
Impact:
Successful exploitation leads to the disclosure of sensitive session cookies, API keys, and authorization bearer tokens to unauthorized third-party redirect targets. This permits session hijacking and unauthorized resource access against automated scraping or crawling agents, with no direct impact on system data integrity or availability.
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Sources:
Reported By: github.com
Extra Source Hub:
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