CVE-2026-42472: MixPHP Framework Deserialization Vulnerability

CVE-2026-42472 Overview

CVE-2026-42472 is an unsafe deserialization vulnerability in the MixPHP Framework affecting versions 2.x through 2.2.17. The framework's session and cache handlers invoke PHP's unserialize() function on data retrieved from Redis through the RedisHandler object. An attacker who can write to the Redis backend can supply a crafted serialized payload that triggers PHP object instantiation and magic method execution. This behavior maps to CWE-502: Deserialization of Untrusted Data and enables remote code execution in the context of the PHP application.

Critical Impact

Successful exploitation allows unauthenticated remote code execution on systems running MixPHP Framework 2.x through 2.2.17 when an attacker can influence Redis-backed session or cache data.

Affected Products

• MixPHP Framework 2.0.x
• MixPHP Framework 2.1.x
• MixPHP Framework 2.x through 2.2.17

Discovery Timeline

• 2026-05-01 - CVE-2026-42472 published to NVD
• 2026-05-05 - Last updated in NVD database

Technical Details for CVE-2026-42472

Vulnerability Analysis

The vulnerability resides in MixPHP's session and cache handling code paths. The RedisHandler class reads serialized data from Redis and passes it directly into PHP's unserialize() function. PHP deserialization reconstructs objects of any class available in the application's autoloader and invokes magic methods such as __wakeup(), __destruct(), and __toString() during object lifecycle events. When attacker-controlled bytes drive this process, gadget chains assembled from framework or third-party library classes can lead to arbitrary file writes, command execution, or further memory corruption inside the PHP runtime.

The Redis sync-invoke server implementation referenced in the MixPHP Server.php source shows where serialized payloads are accepted and processed. A demonstration payload is published in this GitHub Gist example.

Root Cause

The root cause is the use of unserialize() against externally sourced bytes without prior integrity validation or schema enforcement. The framework treats Redis as a trusted store, but Redis instances are frequently exposed without authentication, shared across services, or reachable from compromised application components. Any attacker who can write to a session or cache key controls the byte stream consumed by unserialize().

Attack Vector

Exploitation proceeds over the network. An attacker writes a serialized PHP object payload to a Redis key that the application later loads as session or cache data. When MixPHP reads the key through the RedisHandler, unserialize() instantiates the attacker-defined object graph and triggers magic methods. With suitable gadget chains in the application's class loader, this yields arbitrary code execution under the PHP-FPM or worker process identity. No authentication or user interaction is required if the Redis backend is reachable or if a separate vulnerability allows writes to it.

No verified proof-of-concept code is provided in the vendor advisory beyond the published references. Refer to the MixPHP repository and the linked gist for technical context.

Detection Methods for CVE-2026-42472

Indicators of Compromise

• Unexpected serialized PHP object payloads in Redis keys used for sessions or cache, particularly strings beginning with O: or a: followed by class names not used by the application.
• PHP-FPM or worker processes spawning shell utilities such as sh, bash, python, or network clients shortly after Redis read operations.
• New or modified files in web root directories created by the PHP process owner without a corresponding deployment event.

Detection Strategies

• Inspect Redis traffic and key contents for serialized payloads referencing classes outside the application's expected session or cache schema.
• Hunt for process lineage where PHP runtime processes invoke command interpreters or outbound network connections following session or cache read activity.
• Apply static analysis to identify call sites of unserialize() operating on data sourced from RedisHandler and confirm whether the upgrade has been applied.

Monitoring Recommendations

• Enable command auditing on Redis instances and forward MONITOR or slowlog data to a centralized log store for review.
• Alert on anomalous child processes of PHP-FPM workers and on writes to web-accessible directories outside CI/CD pipelines.
• Track outbound connections from application servers to unfamiliar destinations following web requests that touch session or cache logic.

How to Mitigate CVE-2026-42472

Immediate Actions Required

• Restrict Redis network exposure to the application tier only and require authentication using the requirepass directive or Redis ACLs.
• Audit Redis keyspaces for unexpected serialized payloads and rotate any session and cache keys that may have been written by untrusted sources.
• Inventory all deployments of MixPHP Framework 2.x and identify instances at or below version 2.2.17.

Patch Information

No fixed version is identified in the published NVD record at the time of writing. Monitor the MixPHP GitHub repository for releases beyond 2.2.17 and apply updates that replace unserialize() with a safe encoding such as JSON or that enforce HMAC-based integrity checks on serialized session and cache data.

Workarounds

• Replace the default RedisHandler session and cache backends with handlers that use JSON encoding instead of PHP serialization.
• Place an HMAC signature around any serialized blob written to Redis and verify it before calling unserialize(), rejecting payloads that fail validation.
• Segment Redis instances per application and disable shared instances that are reachable from lower-trust services or shared hosting tenants.

# Example: enforce Redis authentication and bind to localhost only
# /etc/redis/redis.conf
bind 127.0.0.1
requirepass <strong-random-secret>
protected-mode yes
rename-command FLUSHALL ""
rename-command CONFIG ""