How severe is GHSA-m8vh-v6r6-w7p6?

No CVSS score has been assigned to GHSA-m8vh-v6r6-w7p6 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-m8vh-v6r6-w7p6?

GHSA-m8vh-v6r6-w7p6 affects the following packages: getgrav/grav (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-m8vh-v6r6-w7p6?

Update getgrav/grav to 1.8.0-beta.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m8vh-v6r6-w7p6 is resolved across your whole dependency graph.

How do I detect GHSA-m8vh-v6r6-w7p6 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getgrav/grav. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-m8vh-v6r6-w7p6 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-m8vh-v6r6-w7p6?

O3 pinpoints whether GHSA-m8vh-v6r6-w7p6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-m8vh-v6r6-w7p6 actively exploited in the wild?

No public exploit code has been indexed for GHSA-m8vh-v6r6-w7p6 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-m8vh-v6r6-w7p6?

GHSA-m8vh-v6r6-w7p6 is classified as CWE-248 (CWE-248). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-m8vh-v6r6-w7p6 published, and has it been updated?

GHSA-m8vh-v6r6-w7p6 was published on December 2, 2025 and was last updated on December 2, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

GHSA-m8vh-v6r6-w7p6

Fix: getgrav/grav@ed640a1

GHSA-m8vh-v6r6-w7p6 is a CWE-248 vulnerability in getgrav/grav. O3 Security confirms whether GHSA-m8vh-v6r6-w7p6 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Grav vulnerable to Denial of Service via Improper Input Handling in 'Supported' Parameter

Also known asCVE-2025-66305

Published

Dec 2, 2025

Updated

Dec 2, 2025

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Dec 2, 2025 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐘getgrav/grav

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Endpoint: admin/config/system
Submenu: Languages
Parameter: Supported
Application: Grav v 1.7.48

Summary

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 the following error:

preg_match(): Unknown modifier 'o' File: /system/src/Grav/Common/Language/Language.php line 244

Once triggered, the site becomes completely unavailable to all users.

Details

Vulnerable Endpoint: POST /admin/config/system
Submenu: Languages
Parameter: Supported

The application dynamically constructs a regular expression using the contents of the Supported field without escaping the input using preg_quote() or proper validation. This allows attackers to inject invalid syntax into the regex engine, crashing the application during language resolution.

Stack trace excerpt:

Whoops \ Exception \ ErrorException (E_WARNING) preg_match(): Unknown modifier 'o' /system/src/Grav/Common/Language/Language.php244

Proof of Concept (PoC)

Payloads:

/

Steps to Reproduce:

Log into the Grav Admin Panel.
Navigate to: Configuration → System → Languages.
Locate the Supported field.
Insert one of the payloads above (e.g., a single slash /).
Click Save.

Observe: All pages in the application begin throwing a fatal error and become inaccessible.

Impact

Application-wide Denial of Service (DoS)
All login and admin views crash with the same error
Potentially exploitable by:
- Admin panel users
- CSRF if misconfigured

References

CWE-1333: Improper Regular Expression
CWE-20: Improper Input Validation

Discoverer

Marcelo Queiroz

by CVE-Hunters

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`getgrav/grav`	all versions	1.8.0-beta.27

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getgrav/grav. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update getgrav/grav to 1.8.0-beta.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m8vh-v6r6-w7p6 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-m8vh-v6r6-w7p6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-m8vh-v6r6-w7p6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

**Endpoint**: `admin/config/system` **Submenu**: `Languages` **Parameter**: `Supported` **Application**: Grav v 1.7.48 --- ## Summary 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 `pre

O3 Security · Impact-Aware SCA

Is GHSA-m8vh-v6r6-w7p6 in your dependencies?

O3 detects GHSA-m8vh-v6r6-w7p6 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works