The TYPO3 extension "Apache Solr for TYPO3 - Enterprise Search" passes every field value returned by content object rendering through PHP's unserialize() function when transferring multi‑value data for the SOLR_CLASSIFICATION, SOLR_MULTIVALUE, and SOLR_RELATION content object types. If user‑generated content stored in the TYPO3 database can reach a field that is indexed by Solr, an attacker can inject malicious object representations that will be unserialized by PHP during indexing, creating a PHP Object Injection surface that could lead to arbitrary code execution.

The vulnerability affects installations running the TYPO3 "Apache Solr for TYPO3 - Enterprise Search" extension. No specific version range is provided in the advisory, so any instance of the extension that uses the affected content object types and allows untrusted data to be indexed may be vulnerable.

The CVSS score of 7.7 assigns the flaw a high severity. EPSS information is unavailable and the issue is not listed in the CISA KEV catalog. Based on the description, it is inferred that attackers would need to create or modify content that ends up in the Solr index, a process that typically occurs via a remote, web‑based vector. Because the flaw causes PHP Object Injection, a skilled attacker could gain control over the PHP runtime and execute arbitrary code, assuming the server environment is not otherwise hardened.