How severe is GHSA-m27r-m6rx-mhm4?

GHSA-m27r-m6rx-mhm4 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-m27r-m6rx-mhm4?

GHSA-m27r-m6rx-mhm4 affects the following packages: laravel/reverb (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-m27r-m6rx-mhm4?

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.

How do I detect GHSA-m27r-m6rx-mhm4 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for laravel/reverb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-m27r-m6rx-mhm4 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is GHSA-m27r-m6rx-mhm4 actively exploited in the wild?

No public exploit code has been indexed for GHSA-m27r-m6rx-mhm4 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-m27r-m6rx-mhm4?

GHSA-m27r-m6rx-mhm4 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 63th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-m27r-m6rx-mhm4?

GHSA-m27r-m6rx-mhm4 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-m27r-m6rx-mhm4 published, and has it been updated?

GHSA-m27r-m6rx-mhm4 was published on January 21, 2026 and was last updated on February 3, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

CRITICAL severity

Laravel Redis Horizontal Scaling Insecure DeserializationGHSA-m27r-m6rx-mhm4

CRITICALFix: laravel/reverb@9ec26f8

GHSA-m27r-m6rx-mhm4 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in laravel/reverb. A fix is available for laravel/reverb — see the affected versions and patch details below.

Also known asCVE-2026-23524

Published

Jan 21, 2026

Updated

Feb 3, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-m27r-m6rx-mhm4.

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘laravel/reverb

Real-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=false to bypass the vulnerable logic entirely.

Credits

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`laravel/reverb`	all versions	1.7.0`composer require laravel/reverb:^1.7.0`

Affected Products

1 product · 1 configurations

Application

reverblaravel

< 1.7.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for laravel/reverb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

### 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 Rever