Grav CMS Flex Objects Plugin Remote Code Execution

Grav CMS before 2.0.13 contains a remote code execution vulnerability in the Flex Objects plugin settings validation that allows authenticated users to execute arbitrary code by uploading a ZIP file containing PHP code. Attackers can bypass routine name validation by using array notation instead of string notation, call the unZip routine with a malicious archive, and write PHP files to the web root for execution.

Casky was already ahead

This CVE exploits attack patterns that Casky's 322matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-72819 is a remote code execution vulnerability in Grav CMS's Flex Objects plugin that affects versions before 2.0.13. An authenticated attacker can exploit insufficient input validation in the plugin's settings to upload a malicious ZIP file containing PHP code, which gets extracted to the web root and executed by the server. The vulnerability is particularly dangerous because it combines weak validation logic (bypassed through array notation tricks) with unrestricted file upload capabilities, allowing attackers to gain complete control over the CMS and underlying server. Organizations running Grav CMS with the Flex Objects plugin enabled are immediately at risk, especially if they allow untrusted users authentication access.

Casky's 322 matched security skills map this attack to MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance), enabling detection of the multi-stage exploitation chain. Claude's extended reasoning analyzes the attack pattern: Initial Access occurs when an authenticated user submits a crafted ZIP file to plugin settings; the vulnerability stems from CWE-94 (Improper Control of Generation of Code) where array notation bypasses string-based validation. Practitioners would see Casky skill findings flagging suspicious POST requests to Flex Objects configuration endpoints with ZIP file uploads, followed by PHP file creation in web-accessible directories—a classic code injection pattern. The skills would identify the validation bypass technique, detect file write operations outside expected directories, and correlate with execution indicators like new PHP processes or web shell access patterns, giving security teams the precise attack context needed for rapid response.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

322 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-72819.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

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