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Moderate severityNVD Advisory· Published Mar 1, 2013· Updated Apr 29, 2026

CVE-2012-6109

CVE-2012-6109

Description

lib/rack/multipart.rb in Rack before 1.1.4, 1.2.x before 1.2.6, 1.3.x before 1.3.7, and 1.4.x before 1.4.2 uses an incorrect regular expression, which allows remote attackers to cause a denial of service (infinite loop) via a crafted Content-Disposion header.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
rackRubyGems
< 1.1.41.1.4
rackRubyGems
>= 1.2.0, < 1.2.61.2.6
rackRubyGems
>= 1.3.0, < 1.3.71.3.7
rackRubyGems
>= 1.4.0, < 1.4.21.4.2

Affected products

25
  • Rack Project/Rack25 versions
    cpe:2.3:a:rack_project:rack:*:*:*:*:*:*:*:*+ 24 more
    • cpe:2.3:a:rack_project:rack:*:*:*:*:*:*:*:*range: <=1.1.3
    • cpe:2.3:a:rack_project:rack:0.1:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:0.2:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:0.3:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:0.4:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:0.9:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:0.9.1:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.0.0:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.0.1:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.1.0:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.1.2:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.2.0:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.2.1:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.2.2:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.2.3:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.2.4:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.0:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.1:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.2:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.3:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.4:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.5:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.3.6:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.4.0:*:*:*:*:*:*:*
    • cpe:2.3:a:rack_project:rack:1.4.1:*:*:*:*:*:*:*

Patches

1
c9f65df37a15

Fix parsing performance for unquoted filenames

https://github.com/rack/rackJames TuckerMay 13, 2012via ghsa
commit
2 files changed · +22 −2
  • lib/rack/multipart.rb+2 −2 modified
    @@ -12,7 +12,7 @@ module Multipart
     MULTIPART = %r|\Amultipart/.*boundary=\"?([^\";,]+)\"?|n
     TOKEN = /[^\s()<>,;:\\"\/\[\]?=]+/
     CONDISP = /Content-Disposition:\s*#{TOKEN}\s*/i
-    DISPPARM = /;\s*(#{TOKEN})=("(?:\\"|[^"])*"|#{TOKEN})*/
+    DISPPARM = /;\s*(#{TOKEN})=("(?:\\"|[^"])*"|#{TOKEN})/
     RFC2183 = /^#{CONDISP}(#{DISPPARM})+$/i
     BROKEN_QUOTED = /^#{CONDISP}.*;\sfilename="(.*?)"(?:\s*$|\s*;\s*#{TOKEN}=)/i
     BROKEN_UNQUOTED = /^#{CONDISP}.*;\sfilename=(#{TOKEN})/i
@@ -31,4 +31,4 @@ def build_multipart(params, first = true)
     end
 
   end
-end
\ No newline at end of file
+end
  • test/spec_multipart.rb+20 −0 modified
    @@ -295,4 +295,24 @@ def multipart_file(name)
       message.should.equal "value must be a Hash"
   end
 
+  should "parse very long unquoted multipart file names" do
+    data = <<-EOF
+--AaB03x\r
+Content-Type: text/plain\r
+Content-Disposition: attachment; name=file; filename=#{'long' * 100}\r
+\r
+contents\r
+--AaB03x--\r
+    EOF
+
+    options = {
+      "CONTENT_TYPE" => "multipart/form-data; boundary=AaB03x",
+      "CONTENT_LENGTH" => data.length.to_s,
+      :input => StringIO.new(data)
+    }
+    env = Rack::MockRequest.env_for("/", options)
+    params = Rack::Utils::Multipart.parse_multipart(env)
+
+    params["file"][:filename].should.equal('long' * 100)
+  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

14

News mentions

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