Date: Mon, 25 Jan 2016 11:38:45 -0800 From: Aaron Patterson <tenderlove@...y-lang.org> To: security@...e.de, rubyonrails-security@...glegroups.com, oss-security@...ts.openwall.com, ruby-security-ann@...glegroups.com Subject: [CVE-2015-7580] Possible XSS vulnerability in rails-html-sanitizer Possible XSS vulnerability in rails-html-sanitizer There is a possible XSS vulnerability in the white list sanitizer in the rails-html-sanitizer gem. This vulnerability has been assigned the CVE identifier CVE-2015-7580. Versions Affected: All. Not affected: None. Fixed Versions: v1.0.3 Impact ------ Carefully crafted strings can cause user input to bypass the sanitization in the white list sanitizer which will can lead to an XSS attack. Vulnerable code will look something like this: <%= sanitize user_input, tags: %w(em) %> All users running an affected release should either upgrade or use one of the workarounds immediately. Releases -------- The FIXED releases are available at the normal locations. Workarounds ----------- Putting the following monkey patch in an initializer can help to mitigate the issue: ``` class Rails::Html::PermitScrubber alias :old_scrub :scrub alias :old_skip_node? :skip_node? def scrub(node) if node.cdata? text = node.document.create_text_node node.text node.replace text return CONTINUE end old_scrub node end def skip_node?(node); node.text?; end end ``` Patches ------- To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset. * 1-0-whitelist_sanitizer_xss.patch - Patch for 1.0 series Credits ------- Thanks to Arnaud Germis, Nate Clark, and John Colvin for reporting this issue. -- Aaron Patterson http://tenderlovemaking.com/ View attachment "1-0-whitelist_sanitizer_xss.patch" of type "text/plain" (2140 bytes) Content of type "application/pgp-signature" skipped
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