CVE-2026-33942 — saloon
CVE-2026-33942 is a Deserialization of Untrusted Data vulnerability in saloonphp/saloon. A fix is available for saloonphp/saloon — see the affected versions and patch details below.
Saloon has insecure deserialization in AccessTokenAuthenticator (object injection / RCE)
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 CVE-2026-33942.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
saloonphp/saloonReal-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
Users of the OAuth2 utilities in Saloon, specifically the AccessTokenAuthenticator class.
Patches
Upgrade to Saloon v4+
Upgrade guide: https://docs.saloon.dev/upgrade/upgrading-from-v3-to-v4
Description
The Saloon PHP library 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 removes PHP serialization from the AccessTokenAuthenticator class requiring users to store and resolve the authenticator manually.
Credits
Saloon thanks @HuajiHD for finding the issue and recommending solutions and @jonpurvis for applying the fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | saloonphp/saloon | all versions | 4.0.0composer require saloonphp/saloon:^4.0.0 |
Affected Products
saloonsaloonDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for saloonphp/saloon, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update saloonphp/saloon to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33942 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
Is CVE-2026-33942 in your dependencies?
Find it across Packagist, including transitive dependencies.