CVE-2026-28783
CRITICAL
GHSA-5fvc-7894-ghp4
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Lifecycle Timeline
3Description
Craft is a content management system (CMS). Prior to 5.9.0-beta.1 and 4.17.0-beta.1, Craft CMS implements a blocklist to prevent potentially dangerous PHP functions from being called via Twig non-Closure arrow functions. In order to be able to successfully execute this attack, you need to either have allowAdminChanges enabled on production, or a compromised admin account, or an account with access to the System Messages utility. Several PHP functions are not included in the blocklist, which could allow malicious actors with the required permissions to execute various types of payloads, including RCEs, arbitrary file reads, SSRFs, and SSTIs. This vulnerability is fixed in 5.9.0-beta.1 and 4.17.0-beta.1.
Analysis
Code injection bypass in Craft CMS before 5.9.0-beta.1/4.17.0-beta.1 via blocklist evasion. Patch available.
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Remediation
Within 24 hours: Identify all Craft CMS instances in your environment and document their versions. Within 7 days: Apply the available patch to upgrade to version 5.9.0-beta.1, 4.17.0-beta.1, or later across all affected systems. …
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External POC / Exploit Code
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