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Auth0 Symfony SDK Vulnerable to Brute Force Authentication Tags of CookieStore SessionsGHSA-9wg9-93h9-j8ch

CRITICALFix: auth0/symfony@9a7294f

GHSA-9wg9-93h9-j8ch is a critical-severity (CVSS 9.1) 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 5, 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 Session cookies of applications using the Auth0 symfony SDK configured with CookieStore have authentication tags that can be brute forced, which may result in unauthorized access.

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

  1. Applications using the Auth0 symfony SDK with version <=5.3.1
  2. Auth0/Symfony SDK uses the Auth0-PHP SDK with version 8.0.0-BETA1 or higher and below 8.14.0.
  3. Session storage configured with CookieStore.

Fix Upgrade Auth0/symfony to v5.4.0. As an additional precautionary measure, we recommend rotating your cookie encryption keys. Note that once updated, any previous session cookies will be rejected.

Acknowledgement Okta would like to thank Félix Charette for discovering this vulnerability.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistauth0/symfonyall versions5.4.0composer require auth0/symfony:^5.4.0

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 5.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9wg9-93h9-j8ch is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

**Overview** Session cookies of applications using the Auth0 symfony SDK configured with CookieStore have authentication tags that can be brute forced, which may result in unauthorized access. **Am I Affected?** You are affected by this vulnerability if you meet the following pre-conditions: 1. Applications using the Auth0 symfony SDK with version <=5.3.1 2. Auth0/Symfony SDK uses the Auth0-PHP SDK with version 8.0.0-BETA1 or higher and below 8.14.0. 3. Session storage configured with CookieStore. **Fix** Upgrade Auth0/symfony to v5.4.0. As an additional precautionary measure, we recommend
O3 Security · Impact-Aware SCA

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Auth0 Symfony SDK Vulnerable to Brute Force…