CVE-2026-23524

Workarounds

If you cannot upgrade to v1.7.0, you should apply the following mitigations:

• Redis Security: Require a strong password for Redis access and ensure the service is only accessible via a private network or local loopback.
• Disable Scaling: If your environment uses only one Reverb node, set REVERB_SCALING_ENABLED=false to bypass the vulnerable logic entirely.

Credits

This vulnerability was discovered and responsibly reported by Mohammad Yaser Abo-Elmaaty @m0h4mmad

This vulnerability affects Laravel Reverb versions prior to v1.7.0 when horizontal scaling is enabled (REVERB_SCALING_ENABLED=true).

The exploitability of this vulnerability is increased because Redis servers are commonly deployed without authentication.

With horizontal scaling enabled, Reverb servers communicate via Redis PubSub. Reverb previously passed data from the Redis channel directly into PHP’s unserialize() function without restricting which classes could be instantiated.

Risk: Remote Code Execution (RCE)

Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.

CVE-2026-23524 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.7.0); upgrading removes the vulnerable code path.

Kodem intelligence

This vulnerability is fixed in Laravel Reverb v1.7.0.

Update your dependency to laravel/reverb: ^1.7.0 immediately.

1. What is CVE-2026-23524? CVE-2026-23524 is a critical-severity insecure deserialization vulnerability in laravel/reverb (composer), affecting versions < 1.7.0. It is fixed in 1.7.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is CVE-2026-23524? CVE-2026-23524 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of laravel/reverb are affected by CVE-2026-23524? laravel/reverb (composer) versions < 1.7.0 is affected.
4. Is there a fix for CVE-2026-23524? Yes. CVE-2026-23524 is fixed in 1.7.0. Upgrade to this version or later.
5. Is CVE-2026-23524 exploitable, and should I be worried? Whether CVE-2026-23524 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-23524 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-23524? Upgrade laravel/reverb to 1.7.0 or later.