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Auth0 Symfony SDK Deserialization of Untrusted Data vulnerabilityGHSA-98j6-67v3-mw34

GHSA-98j6-67v3-mw34 is a remote code execution vulnerability in auth0/symfony. A fix is available for auth0/symfony — see the affected versions and patch details below.

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Feb 4, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
🐘auth0/symfony

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

Overview The Auth0 Symfony SDK contains a critical vulnerability due to insecure deserialization of cookie data. If exploited, since SDKs process cookie content without prior authentication, a threat actor could send a specially crafted cookie containing malicious serialized data.

Am I Affected? You are affected by this vulnerability if you meet the following preconditions:

  1. Applications using the Auth0 Symfony SDK, versions between 5.0.0 BETA-0 to 5.0.0.
  2. Auth0 Symfony SDK uses the Auth0-PHP SDK with version 8.0.0-BETA3 to 8.3.0.

Fix Upgrade Auth0/symfony to the latest version (v5.4.0).

Acknowledgement Okta would like to thank Andreas Forsblom for discovering this vulnerability.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistauth0/symfony≥ 5.0.0-BETA0&&< 5.1.05.1.0composer require auth0/symfony:^5.1.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for auth0/symfony, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update auth0/symfony to 5.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-98j6-67v3-mw34 is resolved across your whole dependency graph.

  3. 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

**Overview** The Auth0 Symfony SDK contains a critical vulnerability due to insecure deserialization of cookie data. If exploited, since SDKs process cookie content without prior authentication, a threat actor could send a specially crafted cookie containing malicious serialized data. **Am I Affected?** You are affected by this vulnerability if you meet the following preconditions: 1. Applications using the Auth0 Symfony SDK, versions between 5.0.0 BETA-0 to 5.0.0. 2. Auth0 Symfony SDK uses the Auth0-PHP SDK with version 8.0.0-BETA3 to 8.3.0. **Fix** Upgrade Auth0/symfony to the latest ve
O3 Security · Impact-Aware SCA

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