system
Describe <CVE-2021-3902>.
user
What is <CVE-2021-3902>?
assistant
An improper restriction of external entities (XXE) vulnerability in dompdf/dompdf's SVG parser allows for Server-Side Request Forgery (SSRF) and deserialization attacks. This issue affects all versions prior to 2.0.0. The vulnerability can be exploited even if the isRemoteEnabled option is set to false. It allows attackers to perform SSRF, disclose internal image files, and cause PHAR deserialization attacks..