GHSA-m27r-m6rx-mhm4
CRITICALLaravel Redis Horizontal Scaling Insecure Deserialization
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
laravel/reverbReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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)
Patches
This vulnerability is fixed in Laravel Reverb v1.7.0.
Update your dependency to laravel/reverb: ^1.7.0 immediately.
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=falseto bypass the vulnerable logic entirely.
Credits
This vulnerability was discovered and responsibly reported by Mohammad Yaser Abo-Elmaaty @m0h4mmad
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | laravel/reverb | all versions | 1.7.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for laravel/reverb. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update laravel/reverb to 1.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m27r-m6rx-mhm4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-m27r-m6rx-mhm4 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-m27r-m6rx-mhm4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-m27r-m6rx-mhm4 in your dependencies?
O3 detects GHSA-m27r-m6rx-mhm4 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.