What is the CVSS score of CVE-2025-66305?

CVE-2025-66305 has a CVSS 3.1 base score of 4.9 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.1%.

Which versions of Grav are affected by CVE-2025-66305?

Organizations using Grav should be aware of moderate risk from CVE-2025-66305 rated CVSS 4.9. Exploitation could compromise the security of affected deployments.. A patch is available.

Is there a public PoC exploit available for CVE-2025-66305?

Yes, a public proof-of-concept exploit is available for CVE-2025-66305. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2025-66305?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.

Grav CVE-2025-66305

EUVD-2025-200105 MEDIUM

Uncaught Exception (CWE-248)

2025-12-01 security-advisories@github.com

GHSA-m8vh-v6r6-w7p6

Denial Of Service XSS Grav

4.9

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

4.9 MEDIUM

AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

EUVD ID Assigned

Mar 15, 2026 - 13:34 euvd

EUVD-2025-200105

Analysis Generated

Mar 15, 2026 - 13:34 vuln.today

Patch released

Mar 15, 2026 - 13:34 nvd

Patch available

PoC Detected

Dec 03, 2025 - 18:50 vuln.today

Public exploit code

CVE Published

Dec 01, 2025 - 22:15 nvd

MEDIUM 4.9

DescriptionGitHub Advisory

Grav is a file-based Web platform. Prior to 1.8.0-beta.27, a Denial of Service (DoS) vulnerability was identified in the "Languages" submenu of the Grav admin configuration panel (/admin/config/system). Specifically, the Supported parameter fails to properly validate user input. If a malformed value is inserted-such as a single forward slash (/) or an XSS test string-it causes a fatal regular expression parsing error on the server. This leads to application-wide failure due to the use of the preg_match() function with an improperly constructed regular expression, resulting in an error. Once triggered, the site becomes completely unavailable to all users. This vulnerability is fixed in 1.8.0-beta.27.

Analysis

Technical ContextAI

Cross-site scripting (XSS) allows injection of client-side scripts into web pages viewed by other users due to insufficient output encoding.

RemediationAI

A vendor patch is available — apply it immediately. Encode all user-supplied output contextually (HTML, JS, URL). Implement Content Security Policy (CSP) headers. Use HTTPOnly and Secure cookie flags.

CVE-2025-66305 vulnerability details – vuln.today

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Grav CVE-2025-66305

Severity by source

CVSS VectorGitHub Advisory

Lifecycle Timeline

DescriptionGitHub Advisory

Analysis

Technical ContextAI

RemediationAI

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External POC / Exploit Code