Update

In #88 we have determined that the bypass this security advisory was created for, was a false positive and as such we have requested that the CVE be rejected.

A bypass has been found that allows an attacker to upload an SVG with persistent XSS.

HTML elements within CDATA needed to be sanitized correctly, as we were converting them to a textnode and therefore, the library wasn't seeing them as DOM elements.

Any data within a CDATA node will now be sanitised using HTMLPurifier. We've also removed many of the HTML and MathML elements from the allowed element list, as without ForiegnObject, they're not legal within the SVG context.

Additional tests have been added to the test suite to account for these new bypasses.

Impact

This impacts all users of the svg-sanitizer library.

Patches

This issue is fixed in 0.16.0 and higher.

Workarounds

There is currently no workaround available without upgrading.

For more information

If you have any questions or comments about this advisory:

Open an issue in Github
Email us at daryll@enshrined.co.uk

References

• GHSA-xrqq-wqh4-5hg2
• https://nvd.nist.gov/vuln/detail/CVE-2023-28426
• darylldoyle/svg-sanitizer@cce18bc
• darylldoyle/svg-sanitizer#88