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Critical

Insufficient entropy in Auth0-PHP cookie encryption allows session cookie forgery

IdentifiersCVE-2026-34236CWE-331· Insufficient Entropy

CVE-2026-34236 affects the Auth0-PHP SDK for Auth0 Authentication and Management APIs. In versions 8.0.0 through before 8.19.0, applications built with the SDK encrypt cookies using insufficient entropy. This weakness can make the cookie encryption key susceptible to brute-force recovery, after which an attacker may be able to forge valid session cookies. The issue is described as affecting applications using the SDK rather than a standalone Auth0 service, and it was fixed in Auth0-PHP 8.19.0.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can allow an attacker to recover or brute-force the cookie encryption key and forge session cookies for affected applications. This can lead to unauthorized access to authenticated sessions and compromise of confidentiality and integrity within the application context. The provided CVSS v3.1 vector indicates high confidentiality impact, high integrity impact, and no direct availability impact.

Mitigation

If you can’t patch tonight, do this now.

If immediate upgrade is not possible, reduce exposure by rotating application secrets and invalidating existing session cookies after remediation, limiting access to authenticated application functionality, and monitoring for anomalous session activity that could indicate forged cookies. Because the flaw is rooted in insufficient entropy in cookie encryption, the primary effective mitigation is to update to the patched version.

Remediation

Patch, then assume compromise.

Upgrade Auth0-PHP to version 8.19.0 or later, which contains the vendor patch for this issue. Ensure all deployed applications using affected Auth0-PHP versions are rebuilt or redeployed with the fixed SDK version.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Auth0Auth0-Phpapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

5 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

5 SOURCESView more in app
What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity4

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-34236
NVD
nvd.nist.gov/vuln/detail/CVE-2026-34236
MITRE CWE · CWE-331
Insufficient Entropy
Vendor Advisory
github.com/auth0/auth0-PHP/security/advisories/GHSA-w3wc-44p4-m4j7
Release Notes
github.com/auth0/auth0-PHP/releases/tag/8.19.0