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Auth0 Symfony SDK has Insufficient Entropy in Cookie Encryption

High severity GitHub Reviewed Published Apr 1, 2026 in auth0/symfony

Package

composer auth0/symfony (Composer)

Affected versions

>= 5.0.0, <= 5.7.0

Patched versions

5.8.0

Description

Impact

In applications built with the Auth0 PHP SDK, cookies are encrypted with insufficient entropy, which may result in threat actors brute-forcing the encryption key and forging session cookies.

Am I Affected?

Consumers are affected if their application meets the following preconditions:

  • It uses the Auth0 Symfony SDK, versions between 5.0.0 and 5.7.0
  • Auth0 Symfony SDK using the Auth0-PHP SDK versions between 8.0.0 to 8.18.0.

Resolution

Upgrade Auth0/symfony-auth0 to version 5.8.0 or greater.

References

@jennyyang-okta jennyyang-okta published to auth0/symfony Apr 1, 2026
Published to the GitHub Advisory Database Apr 3, 2026
Reviewed Apr 3, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS score

Weaknesses

Insufficient Entropy

The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-ghc5-95c2-vwcv

Source code

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