How severe is CVE-2026-55590?

No CVSS score has been assigned to CVE-2026-55590 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-55590?

CVE-2026-55590 affects the following packages: cakephp/authentication (Packagist), cakephp/authentication (Packagist), cakephp/authentication (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-55590?

Update cakephp/authentication to 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55590 is resolved across your whole dependency graph.

How do I detect CVE-2026-55590 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cakephp/authentication, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-55590 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2026-55590 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-55590 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-55590?

CVE-2026-55590 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 42th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-55590?

CVE-2026-55590 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-55590 published, and has it been updated?

CVE-2026-55590 was published on July 9, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-55590: authentication

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55590.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

3 pkgs affected

🐘cakephp/authentication🐘cakephp/authentication🐘cakephp/authentication

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

CakePHP Authentication is an authentication plugin for CakePHP that can also be used in PSR-7 based applications. Prior to 2.11.1, 3.3.6, and 4.1.1, the getLoginRedirect() method contains a weakness to backslash bypasses that allows redirect targets with attacker-controlled hostnames through the redirect query string parameter. This issue is fixed in versions 2.11.1, 3.3.6, and 4.1.1.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`cakephp/authentication`	≥ 3.0.0&&< 3.3.6	3.3.6`composer require cakephp/authentication:^3.3.6`
🐘Packagist	`cakephp/authentication`	≥ 4.0.0&&< 4.1.1	4.1.1`composer require cakephp/authentication:^4.1.1`
🐘Packagist	`cakephp/authentication`	all versions	2.11.1`composer require cakephp/authentication:^2.11.1`

Affected Products

1 product · 3 configurations

Application

cakephpcakephp

≥ 4.0.0 && < 4.1.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cakephp/authentication, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update cakephp/authentication to 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55590 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

CakePHP Authentication is an authentication plugin for CakePHP that can also be used in PSR-7 based applications. Prior to 2.11.1, 3.3.6, and 4.1.1, the getLoginRedirect() method contains a weakness to backslash bypasses that allows redirect targets with attacker-controlled hostnames through the redirect query string parameter. This issue is fixed in versions 2.11.1, 3.3.6, and 4.1.1.

O3 Security · Impact-Aware SCA

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CVE-2026-55590 — authentication