CVE-2026-23524 is a critical vulnerability affecting Laravel Reverb, a real-time WebSocket backend for Laravel applications, in versions 1.6.3 and below. The vulnerability stems from insecure deserialization (CWE-502) where data received from Redis channels is directly passed into PHP's unserialize() function without any restrictions on which classes can be instantiated. This allows attackers to craft malicious serialized payloads that, when deserialized, can execute arbitrary PHP code remotely, leading to Remote Code Execution (RCE). The risk is heightened because Redis servers are often deployed without authentication, making it easier for attackers to publish malicious payloads to Redis channels. However, the vulnerability only manifests when horizontal scaling is enabled in Reverb (REVERB_SCALING_ENABLED=true), as this triggers the vulnerable deserialization logic. The flaw impacts confidentiality, integrity, and availability, as attackers can execute arbitrary commands, manipulate data, or disrupt services. The issue was addressed in Laravel Reverb version 1.7.0 by presumably adding class restrictions or sanitizing deserialization inputs. Workarounds include enforcing strong Redis authentication, restricting Redis access to private or loopback networks, or disabling horizontal scaling if only a single Reverb node is used. No known exploits are currently reported in the wild, but the high CVSS score (9.8) indicates a critical risk if exploited.

For European organizations, this vulnerability poses a severe risk due to the potential for unauthenticated remote code execution on backend servers running Laravel Reverb with horizontal scaling enabled. Successful exploitation can lead to full system compromise, data breaches, service disruption, and lateral movement within networks. Organizations relying on real-time communication features in Laravel applications, especially those using Redis without authentication or exposed to public networks, are particularly vulnerable. The impact extends to critical sectors such as finance, healthcare, and government services where Laravel is used for web applications requiring real-time updates. The ability to execute arbitrary code without authentication means attackers can bypass most security controls, potentially leading to data theft, ransomware deployment, or infrastructure sabotage. The vulnerability also threatens the integrity and availability of services, which can cause significant operational and reputational damage. Given the widespread use of Redis and Laravel in Europe, the threat landscape is substantial, especially in environments with misconfigured Redis instances or where horizontal scaling is enabled without proper safeguards.

1. Upgrade Laravel Reverb to version 1.7.0 or later immediately to apply the official patch that fixes the deserialization vulnerability. 2. Enforce strong authentication on Redis servers by configuring robust passwords and enabling Redis ACLs to restrict access. 3. Restrict Redis access to private networks or localhost interfaces to prevent unauthorized external connections. 4. If horizontal scaling is not required, set REVERB_SCALING_ENABLED=false to disable the vulnerable deserialization logic. 5. Implement network segmentation and firewall rules to isolate Redis servers from untrusted networks. 6. Monitor Redis channels and application logs for suspicious serialized payloads or unusual activity indicative of exploitation attempts. 7. Conduct regular security audits and penetration tests focusing on deserialization vulnerabilities and Redis configurations. 8. Educate development and operations teams about secure serialization practices and the risks of deserializing untrusted data. 9. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block malicious serialized payloads targeting PHP unserialize functions. 10. Maintain an incident response plan to quickly address potential exploitation events involving Laravel Reverb.