CVE-2024-32463 (published 2024-04-17T16:15Z)

phlex is an open source framework for building object-oriented views in Ruby. There is a potential cross-site scripting (XSS) vulnerability that can be exploited via maliciously crafted user data. The filter to detect and prevent the use of the `javascript:` URL scheme in the `href` attribute of an `<a>` tag could be bypassed with tab `\\t` or newline `\\n` characters between the characters of the protocol, e.g. `java\\tscript:`. This vulnerability is fixed in 1.10.1, 1.9.2, 1.8.3, 1.7.2, 1.6.3, 1.5.3, and 1.4.2. Configuring a Content Security Policy that does not allow `unsafe-inline` would effectively prevent this vulnerability from being exploited.


Weakness information:
cwe_id: NVD-CWE-noinfo
cwe_name: Insufficient Information
description: There is insufficient information about the issue to classify it; details are unkown or unspecified.
extended_description: Insufficient Information

Fix information:
repo_url: https://github.com/phlex-ruby/phlex
commit_details: repo_url: https://github.com/phlex-ruby/phlex
author: Joel Drapper
author_date: 2024-04-16 22:31:35+01:00
msg: Fix XSS
repository: repo_url: https://github.com/phlex-ruby/phlex
repo_name: phlex-ruby/phlex
description: A framework for building object-oriented views in Ruby.
repo_language: Ruby
owner: phlex-ruby
file_changes: filename: sgml.rb
change_type: ModificationType.MODIFY
diff: @@ -382,7 +382,7 @@ module Phlex
 				end
 
 				lower_name = name.downcase
-				next if lower_name == "href" && v.start_with?(/\s*javascript:/i)
+				next if lower_name == "href" && v.to_s.downcase.tr("\t \n", "").start_with?("javascript:")
 
 				# Detect unsafe attribute names. Attribute names are considered unsafe if they match an event attribute or include unsafe characters.
 				if HTML::EVENT_ATTRIBUTES.include?(lower_name) || name.match?(/[<>&"']/)

programming_language: Ruby
filename: naughty_business.rb
change_type: ModificationType.MODIFY
diff: @@ -85,6 +85,78 @@ describe Phlex::HTML do
 		end
 	end
 
+	with "naughty javascript link protocol with a hidden tab character" do
+		view do
+			def view_template
+				a(href: "\tjavascript:alert(1)") { "XSS" }
+				a(href: "j\tavascript:alert(1)") { "XSS" }
+				a(href: "ja\tvascript:alert(1)") { "XSS" }
+				a(href: "jav\tascript:alert(1)") { "XSS" }
+				a(href: "java\tscript:alert(1)") { "XSS" }
+				a(href: "javas\tcript:alert(1)") { "XSS" }
+				a(href: "javasc\tript:alert(1)") { "XSS" }
+				a(href: "javascr\tipt:alert(1)") { "XSS" }
+				a(href: "javascri\tpt:alert(1)") { "XSS" }
+				a(href: "javascrip\tt:alert(1)") { "XSS" }
+				a(href: "javascript\t:alert(1)") { "XSS" }
+				a(href: "javascript:\talert(1)") { "XSS" }
+			end
+		end
+
+		it "strips the javascript protocol" do
+			expect(output.scan("<a>").size).to be == 12
+			expect(output.scan("href").size).to be == 0
+		end
+	end
+
+	with "naughty javascript link protocol with a hidden newline character" do
+		view do
+			def view_template
+				a(href: "\njavascript:alert(1)") { "XSS" }
+				a(href: "j\navascript:alert(1)") { "XSS" }
+				a(href: "ja\nvascript:alert(1)") { "XSS" }
+				a(href: "jav\nascript:alert(1)") { "XSS" }
+				a(href: "java\nscript:alert(1)") { "XSS" }
+				a(href: "javas\ncript:alert(1)") { "XSS" }
+				a(href: "javasc\nript:alert(1)") { "XSS" }
+				a(href: "javascr\nipt:alert(1)") { "XSS" }
+				a(href: "javascri\npt:alert(1)") { "XSS" }
+				a(href: "javascrip\nt:alert(1)") { "XSS" }
+				a(href: "javascript\n:alert(1)") { "XSS" }
+				a(href: "javascript:\nalert(1)") { "XSS" }
+			end
+		end
+
+		it "strips the javascript protocol" do
+			expect(output.scan("<a>").size).to be == 12
+			expect(output.scan("href").size).to be == 0
+		end
+	end
+
+	with "naughty javascript link protocol with a hidden whitespace character" do
+		view do
+			def view_template
+				a(href: " javascript:alert(1)") { "XSS" }
+				a(href: "j avascript:alert(1)") { "XSS" }
+				a(href: "ja vascript:alert(1)") { "XSS" }
+				a(href: "jav ascript:alert(1)") { "XSS" }
+				a(href: "java script:alert(1)") { "XSS" }
+				a(href: "javas cript:alert(1)") { "XSS" }
+				a(href: "javasc ript:alert(1)") { "XSS" }
+				a(href: "javascr ipt:alert(1)") { "XSS" }
+				a(href: "javascri pt:alert(1)") { "XSS" }
+				a(href: "javascrip t:alert(1)") { "XSS" }
+				a(href: "javascript :alert(1)") { "XSS" }
+				a(href: "javascript: alert(1)") { "XSS" }
+			end
+		end
+
+		it "strips the javascript protocol" do
+			expect(output.scan("<a>").size).to be == 12
+			expect(output.scan("href").size).to be == 0
+		end
+	end
+
 	Phlex::HTML::EVENT_ATTRIBUTES.each do |event_attribute|
 		with "with naughty #{event_attribute} attribute" do
 			naughty_attributes = { event_attribute => "alert(1);" }

programming_language: Ruby