CVE-2026-33942 Saloon has insecure deserialization in AccessTokenAuthenticator (object injection / RCE)
An attacker can achieve remote code execution by supplying malicious serialized data to the OAuth token authenticator in this PHP library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33942?
CVE-2026-33942 is a high-severity unsafe deserialization vulnerability in saloonphp saloon, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Saloon is a PHP library that gives users tools to build API integrations and SDKs. Versions prior to 4.0.0 used PHP's unserialize() in AccessTokenAuthenticator::unserialize() to restore OAuth token state from cache or storage, with allowed_classes => true. An attacker who can control the serialized string (e.g. by overwriting a cached token file or via another injection) can supply a serialized "gadget" object. When unserialize() runs, PHP instantiates that object and runs its magic methods (__wakeup, __destruct, etc.), leading to object injection. In environments with common dependencies (e.g. Monolog), this can be chained to remote code execution (RCE). The fix in version 4.0.0 removes PHP serialization from the AccessTokenAuthenticator class requiring users to store and resolve the authenticator manually.
Weakness: CWE-502
Which versions are affected by CVE-2026-33942?
2 open source packages ship an affected version, including saloonphp/saloon. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
saloonphp/saloon Packagist | All versions | 4.0.0 |
saloonphp/saloon Packagist | All versions | 4.0.0 |
Products include Saloon Saloon.
How do I fix CVE-2026-33942?
Upgrade saloonphp/saloon to 4.0.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-33942 being exploited?
There is no known exploitation of CVE-2026-33942 in the wild and no public exploit code.
Other vulnerabilities in saloonphp saloon
Sources
Also known as CVE-2026-33181, GHSA-rf88-776r-rcq9.