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Vulnerabilities

Vulnerability · GHSA-9hp6-3565-gvh5

Control panel only API response emulation replaces "securityKey" and reaches server RCE

Published Oct 23, 2026 · catalog updated Oct 23, 2026 · Control panel only API

Last checked Nov 1, 2026. A connected source was read within the last 7 days.

Open the advisory

Exploitation likelihood is not on this record for GHSA-9hp6-3565-gvh5. A missing EPSS score is not a low risk. Compare Control panel only API with the linked advisory before you change production.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Control panel only API).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
  • EPSS is missing. A missing score is not a low risk.
Severity
High—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
Awaiting synchronization with FIRST
Remediation
Version ranges on file
Affected products
composer craftcms/cms

The action accepts fake Craft API response headers from any authenticated control panel user. A non-admin user with only can place newline characters in . Craft passes this value to its writer without removing the newlines. This lets the user insert a new attacker-known into . After Craft loads that key, the user can forge a signed login redirect containing a Twig callback. This is different from the previous report. That report reads the existing key through a Twig sandbox bypass. This report replaces the key through fake API headers and CRLF injection. Fixing either source does not fix the other. ### Impact A low-privileged control panel account can execute arbitrary operating system commands as the PHP worker. Report ID: 1899

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • composer craftcms/cms>= 4.0.0, < 4.18.9
  • composer craftcms/cms>= 5.0.0, < 5.11.2

How to fix GHSA-9hp6-3565-gvh5

  • Upgrade

    GHSA-9hp6-3565-gvh5 lists a fix boundary at 4.18.9. Compare the installed build with that boundary before you change production.

  • Version check

    Affected < 4.18.9

  • Advisory

    Open the inventory_github record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

Exploitation likelihood is not on this record for GHSA-9hp6-3565-gvh5. A missing EPSS score is not a low risk. Compare Control panel only API with the linked advisory before you change production.

Which versions are affected?

Compare what you have installed with >= 4.0.0, < 4.18.9, >= 5.0.0, < 5.11.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-94: Code Injection. EPSS is not on this record yet. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Craft CMS security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Maintainer security tabs

    Detected

    The action accepts fake Craft API response headers from any authenticated control panel user. A non-admin user with only can place newline characters in . Craft passes this value to its writer without removing the newlines. This lets the user insert a new attacker-known into . After Craft loads that key, the user can forge a signed login redirect containing a Twig callback. This is different from

Sources

  • Maintainer security tabsVendor advisoryGHSA-9hp6-3565-gvh5

    The action accepts fake Craft API response headers from any authenticated control panel user. A non-admin user with only can place newline characters in . Craft passes this value to its writer without removing the newlines. This lets the user insert a new attacker-known into . After Craft loads that key, the user can forge a signed login redirect containing a Twig callback. This is different from

    github.com

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Maintainer security tabsNov 1, 2026