CVE-2021-33512 Cross-site scripting in Plone

What is CVE-2021-33512?

CVE-2021-33512 is a medium-severity cross-site scripting vulnerability in Plone Plone, published on 21 May 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Plone through 5.2.4 allows stored XSS attacks (by a Contributor) by uploading an SVG or HTML document.

Weakness: CWE-79

Which versions are affected by CVE-2021-33512?

3 open source packages ship an affected version, including plone and Plone. It affects 1 product.

Products include Plone Plone.

How do I fix CVE-2021-33512?

Upgrade plone to 5.2.5 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-33512 being exploited?

There is no known exploitation of CVE-2021-33512 in the wild and no public exploit code.

Other vulnerabilities in Plone Plone

• CVE-2021-33509 Incorrect Permission Assignment for Critical Resource in Plone Critical 9.9
• CVE-2020-35190 Hardcoded credentials in n/a Critical 9.8
• CVE-2020-7941 Plone Unauthenticated Write Vulnerability Critical 9.8
• CVE-2011-3587 Zope Command Execution Vulnerability Critical 9.3
• CVE-2021-33926 Server-Side Request Forgery in Plone CMS High 8.8

All Plone Plone vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-hm2h-f456-6j88, PYSEC-2021-84.