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GHSA-22wq-q86m-83fh
No affected components available
Problem
The sanitization logic at https://github.com/darylldoyle/svg-sanitizer/blob/0.21.0/src/Sanitizer.php#L454-L481 only searches for lower-case attribute names (e.g. xlink:href instead of xlink:HrEf), which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains.
Proof-of-concept
provided by azizk
<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100">
<a xlink:hReF="javascript:alert(document.domain)">
<rect width="100" height="50" fill="red"></rect>
<text x="50" y="30" text-anchor="middle" fill="white">Click me</text>
</a>
</svg>
Credits
The mentioned findings and proof-of-concept example were reported to the TYPO3 Security Team by the external security researcher azizk <medazizknani@gmail.com>.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights.
Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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