Weak Auth0-PHP cookie encryption enables session cookie forgery
TL;DR — Insufficient entropy in Auth0-PHP’s cookie encryption can enable attackers to brute-force the encryption key and forge session cookies, potentially turning into a practical auth bypass in impacted apps.
What happened
auth0/auth0-php is a PHP SDK used to integrate Auth0 Authentication and Management APIs into applications.
CVE-2026-34236 reports that, in impacted versions, cookies are encrypted with insufficient entropy, which may allow threat actors to brute-force the encryption key and then forge session cookies. The CVE record scores this as CVSS v3.1 8.2 (High).
Session cookie integrity failures are high-signal because they can collapse application trust boundaries: once attackers can forge an authenticated session artifact, many downstream authorization controls become irrelevant.
Who is impacted
- Applications using
auth0/auth0-phpversions>= 8.0.0, < 8.19.0.
| Component | Affected versions (per CVE record) | Patched versions / solution status |
|---|---|---|
auth0-PHP (auth0/auth0-php) | >= 8.0.0, < 8.19.0 | Patched in 8.19.0 |
What to do now
- Follow vendor remediation guidance and apply the latest patched release available at the time of writing.
- If you use Auth0 in PHP services, inventory where
auth0/auth0-phpis deployed (lockfiles, built artifacts, container images) and map instances to the affected range. - Prioritize patching for internet-facing apps and any services where session cookies protect high-value actions (admin consoles, billing, user-management, and token minting flows).
Content is AI-assisted and reviewed by our team, but issues may be missed and best practices evolve rapidly, send corrections to [email protected]. Always consult official documentation and validate key implementation decisions before making design or security choices.