Auth0 Symfony SDK has Insufficient Entropy in Cookie Encryption

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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.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-04-03 03:44:13 UTC
Updated
2026-04-03 03:44:13 UTC
GitHub reviewed
2026-04-03 03:44:13 UTC

CVSS Scores

Base score Version Severity Vector
8.2 3.1 —
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-ghc5-95c2-vwcv ↗

CWEs

CWE id Name
CWE-331 Insufficient Entropy

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
composer auth0/symfony >= 5.0.0, <= 5.7.0 5.8.0 —

References

cvelogic Threat Intelligence