Insecure Deserialization/Unsafe Attributes Merge

phenx/php-svg-lib is vulnerable to Insecure Deserialization. The vulnerability is caused due to unsafe attributes such as href, xlink:href and id while merging attributes from the tag to the tag when handling a tag that references an tag. This can lead to an unsafe file read that can cause PHAR Deserialization vulnerability in PHP < 8 when the href attribute from the `` tag has not been sanitized leading to insecure deserialization or even RCE.