Saloon has insecure deserialization in AccessTokenAuthenticator

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U · score source

EPSS

• CVE-2026-33942: 0.63% estimated exploitation activity in the next 30 days; percentile 50.33 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 allowedclasses = 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…

Published by the source

27 Mar 2026, 18:33 UTC

Last modified by the source

27 Mar 2026, 18:33 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rf88-776r-rcq9

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# Patch Next advisory brief: CVE-2026-33942

Advisory: Saloon has insecure deserialization in AccessTokenAuthenticator
IDs: CVE-2026-33942, GHSA-rf88-776r-rcq9
Record: https://patchnext.com/advisories/cve-2026-33942 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: saloonphp/saloon 4.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist saloonphp/saloon: affected < 4.0.0; fixed in 4.0.0

## Suggested inspection (read-only)
- Packagist saloonphp/saloon: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on saloonphp/saloon.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rf88-776r-rcq9 (GitHub-reviewed advisory GHSA-rf88-776r-rcq9 lists affected ranges: Packagist saloonphp/saloon >=0 <4.0.0)

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