Vulnerability · Published Oct 23, 2026 · Assigned by Hackrate

CVE-2026-115935Control panel only API response emulation replaces "securityKey" and reaches server RCE

High 8.8

In plain English

A high-severity code injection in cms from craftcms. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.4%top 69.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

The app/process-api-response-headers action accepts fake Craft API response headers from any authenticated control panel user. A non-admin user with only accessCp can place newline characters in X-Craft-Plugin-Licenses. Craft passes this value to its .env writer without removing the newlines. This lets the user insert a new attacker-known CRAFT_SECURITY_KEY into .env. After Craft loads that key, the user can forge a signed login redirect containing a Twig system() 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.

Affected products (as reported)

Vendor	Product	Versions
craftcms	cms	5.0.0 – before 5.11.24.0.0 – before 4.18.9

Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

https://www.hckrt.com/hacktivity/HCKRT-WM3VSE third-party-advisory, technical-description, mitigation
https://github.com/craftcms/cms/releases/tag/5.11.2 release-notes
https://github.com/craftcms/cms product
https://github.com/craftcms/cms/security/advisories/GHSA-9hp6-3565-gvh5 third-party-advisory