Vulnerability-Lookup

GHSA-M8VH-V6R6-W7P6

Vulnerability from github – Published: 2025-12-02 00:46 – Updated: 2025-12-02 00:46

Summary

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

Details

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.

Pasted image 20250719183223

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

Pasted image 20250719175229

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

Severity

8.2 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "getgrav/grav"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.8.0-beta.27"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-66305"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-02T00:46:05Z",
    "nvd_published_at": "2025-12-01T22:15:50Z",
    "severity": "HIGH"
  },
  "details": "**Endpoint**: `admin/config/system`  \n**Submenu**: `Languages`  \n**Parameter**: `Supported`  \n**Application**: Grav v 1.7.48\n\n---\n\n## Summary\n\nA 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\u2014such as a single forward slash (`/`) or an XSS test string\u2014it causes a fatal regular expression parsing error on the server.\n\nThis 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:\n\n`preg_match(): Unknown modifier \u0027o\u0027 File: /system/src/Grav/Common/Language/Language.php line 244`\n\nOnce triggered, the site becomes completely unavailable to all users.\n\n---\n\n## Details\n\n- **Vulnerable Endpoint**: `POST /admin/config/system`\n    \n- **Submenu**: `Languages`\n    \n- **Parameter**: `Supported`  \n    \n\nThe 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.\n\n**Stack trace excerpt**:\n\n`Whoops \\ Exception \\ ErrorException (E_WARNING) preg_match(): Unknown modifier \u0027o\u0027 /system/src/Grav/Common/Language/Language.php244`\n\n---\n\n## Proof of Concept (PoC)\n\n### Payloads:\n\n`/ `\n\n### Steps to Reproduce:\n\n1. Log into the Grav Admin Panel.\n    \n2. Navigate to: **Configuration** \u2192 **System** \u2192 **Languages**.\n    \n3. Locate the `Supported` field.\n    \n4. Insert one of the payloads above (e.g., a single slash `/`).\n    \n5. Click **Save**.\n\n\u003cimg width=\"1897\" height=\"639\" alt=\"Pasted image 20250719183223\" src=\"https://github.com/user-attachments/assets/d3a54a20-d30d-46c6-9015-722f80701cfb\" /\u003e\n\n1. Observe: All pages in the application begin throwing a fatal error and become inaccessible.\n\n\u003cimg width=\"1802\" height=\"998\" alt=\"Pasted image 20250719175229\" src=\"https://github.com/user-attachments/assets/b16750c2-507f-4c30-a9bb-d07fa92bb777\" /\u003e\n\n---\n\n## Impact\n\n- Application-wide Denial of Service (DoS)\n    \n- All login and admin views crash with the same error\n    \n- Potentially exploitable by:\n    \n    - Admin panel users\n        \n    - CSRF if misconfigured        \n    \n\n---\n\n## References\n\n- **CWE-1333**: Improper Regular Expression\n    \n- **CWE-20**: Improper Input Validation\n\n\n## Discoverer\n\n[Marcelo Queiroz](www.linkedin.com/in/marceloqueirozjr) \n\nby [CVE-Hunters](https://github.com/Sec-Dojo-Cyber-House/cve-hunters)",
  "id": "GHSA-m8vh-v6r6-w7p6",
  "modified": "2025-12-02T00:46:05Z",
  "published": "2025-12-02T00:46:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-m8vh-v6r6-w7p6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66305"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/commit/ed640a13143c4177af013cf001969ed2c5e197ee"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/getgrav/grav"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Grav vulnerable to Denial of Service via Improper Input Handling in \u0027Supported\u0027 Parameter"
}

CVE-2025-66305 (GCVE-0-2025-66305)

Vulnerability from cvelistv5 – Published: 2025-12-01 21:43 – Updated: 2025-12-02 20:14

Title

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

Summary

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.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-12-02 20:14 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

GitHub_M mitre root Scorecard

References

2 references

URL	Tags
https://github.com/getgrav/grav/security/advisori…	x_refsource_CONFIRM
https://github.com/getgrav/grav/commit/ed640a1314…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
getgrav	grav	Affected: < 1.8.0-beta.27

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-66305",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-12-02T20:14:17.748570Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-12-02T20:14:21.770Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/getgrav/grav/security/advisories/GHSA-m8vh-v6r6-w7p6"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "grav",
          "vendor": "getgrav",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.0-beta.27"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u2014such as a single forward slash (/) or an XSS test string\u2014it 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "HIGH",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-248",
              "description": "CWE-248: Uncaught Exception",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-01T21:43:29.725Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/getgrav/grav/security/advisories/GHSA-m8vh-v6r6-w7p6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/getgrav/grav/security/advisories/GHSA-m8vh-v6r6-w7p6"
        },
        {
          "name": "https://github.com/getgrav/grav/commit/ed640a13143c4177af013cf001969ed2c5e197ee",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/getgrav/grav/commit/ed640a13143c4177af013cf001969ed2c5e197ee"
        }
      ],
      "source": {
        "advisory": "GHSA-m8vh-v6r6-w7p6",
        "discovery": "UNKNOWN"
      },
      "title": "Grav vulnerable to Denial of Service via Improper Input Handling in \u0027Supported\u0027 Parameter"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-66305",
    "datePublished": "2025-12-01T21:43:29.725Z",
    "dateReserved": "2025-11-26T23:11:46.395Z",
    "dateUpdated": "2025-12-02T20:14:21.770Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-M8VH-V6R6-W7P6

Summary

Details

Proof of Concept (PoC)

Payloads:

Steps to Reproduce:

Impact

References

Discoverer

CVE-2025-66305 (GCVE-0-2025-66305)

Tags

Sightings

Nomenclature

Related by attack behaviour