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Grav EUVDEUVD-2025-200111

| CVE-2025-66299 HIGH
Code Injection (CWE-94)
2025-12-01 security-advisories@github.com GHSA-gjc5-8cfh-653x
8.8
CVSS 3.1 · Vendor: github
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Code injection prevention, sandbox exec
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

Complete system compromise — the attacker gains the ability to install malware, steal data, create backdoors, or pivot to other systems on the network. With a CVSS score of 8.8 (HIGH), this represents a significant risk.

Exploit ScenarioDerived

An attacker sends a specially crafted request to the vulnerable service that triggers code execution with the privileges of the running process.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

Grav is a file-based Web platform. Prior to 1.8.0-beta.27, Grav CMS is vulnerable to a Server-Side Template Injection (SSTI) that allows any authenticated user with editor permissions to execute arbitrary code on the remote server, bypassing the existing security sandbox. Since the security sandbox does not fully protect the Twig object, it is possible to interact with it (e.g., call methods, read/write attributes) through maliciously crafted Twig template directives injected into a web page. This allows an authenticated editor to add arbitrary functions to the Twig attribute system.twig.safe_filters, effectively bypassing the Grav CMS sandbox. This vulnerability is fixed in 1.8.0-beta.27.

Earlier versions of this analysis (1)
v1 Mar 15, 2026 - 13:34 CVSS 8.8

RemediationAI

A vendor patch is available — apply it immediately. Apply vendor patches immediately. Restrict network access to vulnerable services. Implement network segmentation and monitoring for anomalous activity.

Affected VersionsENISA

grav < 1.8.0-beta.27

Affected Packages

composer getgrav/grav fix: 1.8.0-beta.27
euvd grav fix: 1.8.0-beta.27

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in composer, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Remote code execution allows an attacker to run arbitrary commands or code on the target system over a network without prior authentication. This vulnerability is classified as Code Injection (CWE-94).

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (github) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from Vendor (github) · only source for this CVE.

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Patch released
Mar 15, 2026 - 13:34 nvd
Patch available
PoC Detected
Dec 03, 2025 - 15:41 vuln.today
Public exploit code
CVE Published
Dec 01, 2025 - 22:15 nvd
HIGH 8.8

Executive ViewAI

Why It Matters

Grav CMS versions prior to 1.8.0-beta.27 contain a critical vulnerability allowing authenticated editors to execute arbitrary code on servers, effectively bypassing security protections. Organizations running affected Grav instances face immediate risk of data breach, system compromise, and operational disruption through insider threats or compromised editor accounts.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Restrict editor role assignments to only essential trusted personnel; (2) implement file integrity monitoring on Grav template directories; (3) deploy WAF rules to detect/block suspicious Twig directives in POST requests; (4) isolate affected Grav instances network-wide and monitor for unauthorized code execution indicators.

Threat Intelligence Overview

EPSS Score
0.1%
Top 72% exploitable
Exploit
POC
Public exploit code exists
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact
High

Priority Score

64
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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