The Qyrr plugin for WordPress, designed for modern QR code creation, suffers from a CWE-434 vulnerability due to improper validation of uploaded file types in the blob_to_file() function. This vulnerability affects all versions up to and including 2.0.7. Authenticated users with Contributor-level privileges or higher can exploit this flaw to upload arbitrary files to the server hosting the WordPress site. Because the plugin fails to restrict or validate the file types being uploaded, attackers can potentially upload malicious scripts or executable files. This can lead to remote code execution (RCE), allowing attackers to execute arbitrary commands on the server, compromising the confidentiality and integrity of the system. The vulnerability is remotely exploitable over the network without requiring user interaction beyond authentication. The CVSS 3.1 base score is 6.4, reflecting a medium severity due to the need for authentication but the high impact on confidentiality and integrity. No public exploits have been reported yet, but the vulnerability is significant given the widespread use of WordPress and the plugin's functionality. The lack of patch links suggests that a fix may not yet be available, increasing the urgency for mitigation. The vulnerability was published on September 30, 2025, with the CVE reserved earlier that month. The issue highlights the risks of insufficient input validation in web applications, especially those handling file uploads.

For European organizations, this vulnerability poses a risk primarily to websites and web applications running WordPress with the Qyrr plugin installed. Successful exploitation could lead to unauthorized file uploads, enabling attackers to execute arbitrary code on web servers. This threatens the confidentiality of sensitive data stored or processed by the affected sites, the integrity of website content, and potentially the availability if the server is destabilized or taken offline. Organizations in sectors such as e-commerce, government, healthcare, and media, which rely heavily on WordPress for their web presence, could face data breaches, defacement, or service disruptions. The requirement for Contributor-level access reduces the attack surface but does not eliminate risk, as many WordPress sites allow user registrations or have multiple contributors. The vulnerability could also be leveraged as a foothold for lateral movement within corporate networks if the web server is connected to internal resources. Given the lack of known exploits, the immediate impact may be limited, but the potential for damage is significant if exploited.

European organizations should immediately audit their WordPress installations to identify the presence of the Qyrr plugin and its version. If the plugin is installed, restrict Contributor-level access strictly to trusted users and consider temporarily disabling or uninstalling the plugin until a patch is available. Implement web application firewall (WAF) rules to detect and block suspicious file upload attempts, especially those targeting the blob_to_file() function or unusual file types. Enforce strict file upload policies, including MIME type validation and file extension whitelisting at the server level. Monitor server logs and WordPress activity logs for anomalous upload behavior or unauthorized file creations. Employ intrusion detection systems (IDS) to alert on potential exploitation attempts. Regularly back up website data and configurations to enable quick recovery in case of compromise. Engage with the plugin vendor or community to track patch releases and apply updates promptly once available. Additionally, consider isolating the web server environment to limit the impact of potential remote code execution.