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High severity8.1NVD Advisory· Published Nov 13, 2017· Updated May 13, 2026

CVE-2017-0904

CVE-2017-0904

Description

The private_address_check ruby gem before 0.4.0 is vulnerable to a bypass due to use of Ruby's Resolv.getaddresses method, which is OS-dependent and should not be relied upon for security measures, such as when used to blacklist private network addresses to prevent server-side request forgery.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
private_address_checkRubyGems
< 0.4.00.4.0

Affected products

2

Patches

1
58a0d7fe31de

Fix bypass bug with malformed addresses

https://github.com/jtdowney/private_address_checkJohn DowneyNov 5, 2017via ghsa
commit
2 files changed · +6 −0
  • lib/private_address_check.rb+2 −0 modified
    @@ -31,6 +31,8 @@ def private_address?(address)
 
   def resolves_to_private_address?(hostname)
     ips = Resolv.getaddresses(hostname)
+    return true if ips.empty?
+
     ips.any? do |ip| 
       private_address?(ip)
     end
  • test/private_address_check_test.rb+4 −0 modified
    @@ -35,4 +35,8 @@ def test_private_hostname_for_public_addresses
   def test_private_hostname_for_private_addresses
     assert PrivateAddressCheck.resolves_to_private_address?("localhost")
   end
+
+  def test_private_address_for_malformed_addresses
+    assert PrivateAddressCheck.resolves_to_private_address?("127.1")
+  end
 end

Vulnerability mechanics

Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

8

News mentions

0

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