How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

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361,925

Total vulnerabilities in the database

Grav is Vulnerable to XXE via SVG Upload — getgrav / grav

Improper Restriction of XML External Entity Reference

Dear Grav Security Team,

A security vulnerability was discovered in Grav CMS that allows authenticated attackers to read arbitrary files from the server through XML External Entity (XXE) injection.

Vulnerability Summary

| Field | Details | |-------|---------| | Vulnerability Type | XML External Entity (XXE) Injection | | Severity | High (CVSS 7.5) | | Affected Versions | Grav CMS <= 1.7.x | | Affected Component | SVG file upload/processing | | CWE | CWE-611: Improper Restriction of XML External Entity Reference | | Authentication Required | Yes (Admin panel access) |

Technical Details

Root Cause The application uses simplexml_load_string() to process uploaded SVG files without disabling external entity loading. This allows attackers to inject XXE payloads that are processed by the XML parser.

Vulnerable Code Pattern

// Current (Vulnerable):
$svg = simplexml_load_string($content);

// No LIBXML_NOENT flag or entity loader protection

Attack Vector

Attacker authenticates to Grav admin panel
Uploads malicious SVG file via Pages → Media or File Manager plugin
Server parses SVG and processes XXE entities
Arbitrary file contents are exfiltrated

Impact

An authenticated attacker can:

Read sensitive files:
- /etc/passwd - System user information
- user/accounts/*.yaml - Admin credentials and 2FA secrets
- user/config/system.yaml - System configuration
- .env files - Environment secrets and API keys
Perform SSRF - Access internal services via external entity URLs
Potential DoS - Billion laughs attack via recursive entity expansion

Proof of Concept

Malicious SVG Payload

&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;!DOCTYPE svg [
  &lt;!ENTITY xxe SYSTEM &quot;file:///etc/passwd&quot;&gt;
]&gt;
&lt;svg xmlns=&quot;http://www.w3.org/2000/svg&quot; width=&quot;100&quot; height=&quot;100&quot;&gt;
  &lt;text x=&quot;10&quot; y=&quot;50&quot;&gt;&amp;xxe;&lt;/text&gt;
&lt;/svg&gt;

Steps to Reproduce

Login to Grav CMS admin panel
Navigate to Pages → select any page → Media tab
Upload the malicious SVG file
Observe file contents in response/error or stored output

Recommended Fix

Option 1: Add XXE Protection Flags

libxml_use_internal_errors(true);
$svg = simplexml_load_string($content, &#039;SimpleXMLElement&#039;, LIBXML_NOENT | LIBXML_DTDLOAD);

Option 2: Use SVG Sanitizer Library (Recommended)

use enshrined\svgSanitize\Sanitizer;

$sanitizer = new Sanitizer();
$sanitizer-&gt;removeRemoteReferences(true);
$cleanSVG = $sanitizer-&gt;sanitize($content);

The enshrined/svg-sanitize library properly strips XXE payloads and other malicious SVG content.

Request

Please acknowledge receipt of this report within 5 business days
Please provide an estimated timeline for a security patch
I am happy to assist with testing the fix
I request a CVE be assigned for this vulnerability
If you have a security advisory process, please include me in the credits

Turki Almatrafi.

Maintainer note — fix applied (2026-04-24)

Fixed across two repos:

Grav core on the 2.0 branch (commit 5a12f9be8, ships in 2.0.0-beta.2) — VectorImageMedium::__construct (the code path that reads width/height from an uploaded SVG) now strips <!DOCTYPE> and <!ENTITY> declarations before parsing, and calls simplexml_load_string with LIBXML_NONET | LIBXML_NOERROR | LIBXML_NOWARNING. On PHP < 8 it also calls libxml_disable_entity_loader(true) for the duration of the parse.
rhukster/dom-sanitizer (commit 02d08ec) — the library Grav ships as its SVG sanitizer. loadDocument now applies the same DOCTYPE/ENTITY strip and passes LIBXML_NONET to loadXML/loadHTML.

With both layers in place, the PoC:

&lt;!DOCTYPE svg [
  &lt;!ENTITY xxe SYSTEM &quot;file:///etc/passwd&quot;&gt;
]&gt;
&lt;svg xmlns=&quot;http://www.w3.org/2000/svg&quot; width=&quot;100&quot; height=&quot;100&quot;&gt;
  &lt;text x=&quot;10&quot; y=&quot;50&quot;&gt;&amp;xxe;&lt;/text&gt;
&lt;/svg&gt;

no longer expands &xxe;, and the parser cannot make outbound filesystem or network requests for external entities/DTDs. Billion-laughs-style entity expansion is also neutralized because the declarations are stripped before libxml ever sees them.

Files:

system/src/Grav/Common/Page/Medium/VectorImageMedium.php.
tests/unit/Grav/Common/Security/SvgXxeSecurityTest.php — XXE neutralization + billion-laughs + plain-SVG regression.
dom-sanitizer: src/DOMSanitizer.php + two new XXE tests in its own suite.

Published: May 5, 2026
Updated: May 6, 2026
GHSA: GHSA-3446-6mgw-f79p
Severity: Medium
Exploit:
CISA KEV:

CVSS v3:

Severity: Medium
Score: 6.5
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CWEs:

CWE-611

OWASP TOP 10:

A4 - XML External Entities (XXE)

Affected Software
References

Software	From	Fixed in
getgrav / grav	-	2.0.0-beta.2

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.