Advisories for Composer/Knplabs/Knp-Snappy package

On POSIX, escapeshellarg(‘/usr/bin/wkhtmltopdf’) returns the literal string ‘/usr/bin/wkhtmltopdf’ with the single-quote characters included. is_executable() then looks for a file whose actual name contains those quote characters, which essentially never exists. The safe branch is dead code and $command always falls through to the raw, unescaped value. The rest of the arguments (options, input, output) are escaped correctly, so injection has to land in the binary string itself. That happens whenever …

It impacts applications where: the PHP daemon run with root permissions ; the application is either running outside a container or has sensitive file access ; It could happens with this kind of workflows: $stylesheet = $_GET['stylesheet']; // = ‘file:///etc/passwd’ $pdf = new Knp\Snappy\Pdf(‘/usr/local/bin/wkhtmltopdf’); $pdf->generate(‘page.html’, ‘out.pdf’, [ ‘xsl-style-sheet’ => $stylesheet ]);

knplabs/knp-snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page. Issue On March 17th the vulnerability CVE-2023-28115 was disclosed, allowing an attacker to gain remote code execution through PHAR deserialization. Version 1.4.2 added a check if (\strpos($filename, 'phar://') === 0) in the prepareOutput function to resolve this CVE, however if the user is able to control the second parameter of the generateFromHtml() …

Snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page. Prior to version 1.4.2, Snappy is vulnerable to PHAR deserialization due to a lack of checking on the protocol before passing it into the file_exists() function. If an attacker can upload files of any type to the server he can pass in the phar:// protocol to unserialize the uploaded file and instantiate …