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Overview

org.jruby:jruby is a high performance, stable, fully threaded Java implementation of the Ruby programming language.

Affected versions of this package are vulnerable to Improper Validation of Certificate with Host Mismatch in the SSL certificate validation process. An attacker can intercept secure communications by presenting a valid certificate for an unrelated domain that the attacker controls.

Note:

This is only exploitable if the attacker is in a "man-in-the-middle" (MITM) position before performing the attack.

PoC

require "net/http"
require "openssl"

uri   = URI("https://bad.substitutealert.com/")
https = Net::HTTP.new(uri.host, uri.port)
https.use_ssl      = true
https.verify_mode  = OpenSSL::SSL::VERIFY_PEER

body = https.start { https.get(uri.request_uri).body }
puts body

Remediation

Upgrade org.jruby:jruby to version 9.4.12.1, 10.0.0.1 or higher.

References

• GitHub Commit

EPL-1.0 license