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CVE-2021-21425— Unauthenticated Arbitrary YAML Write/Update leads to Code Execution

Quick assessment

Affected
getgrav grav-plugin-admin
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Grav是一套可扩展的用于个人博客、小型内容发布平台和单页产品展示的CMS（内容管理系统）。 Grav 存在安全漏洞，该漏洞源于未经身份验证的用户可以执行管理员控制器的一些方法，而不需要任何凭据。

CVSS 9.3 · Critical EPSS 80.60% · P100

Public Exploits 2

ExploitDB · 1 EDB-49788 [webapps]
Metasploit · 1 gravcms_exec.rb [exploit]
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I. Basic Information for CVE-2021-21425

Vulnerability Information
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Vulnerability Title
Unauthenticated Arbitrary YAML Write/Update leads to Code Execution
Source: CVE Program / CVE List V5
Vulnerability Description
Grav Admin Plugin is an HTML user interface that provides a way to configure Grav and create and modify pages. In versions 1.10.7 and earlier, an unauthenticated user can execute some methods of administrator controller without needing any credentials. Particular method execution will result in arbitrary YAML file creation or content change of existing YAML files on the system. Successfully exploitation of that vulnerability results in configuration changes, such as general site information change, custom scheduler job definition, etc. Due to the nature of the vulnerability, an adversary can change some part of the webpage, or hijack an administrator account, or execute operating system command under the context of the web-server user. This vulnerability is fixed in version 1.10.8. Blocking access to the `/admin` path from untrusted sources can be applied as a workaround.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Grav 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Grav是一套可扩展的用于个人博客、小型内容发布平台和单页产品展示的CMS（内容管理系统）。 Grav 存在安全漏洞，该漏洞源于未经身份验证的用户可以执行管理员控制器的一些方法，而不需要任何凭据。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
getgrav grav-plugin-admin <= 1.10.7 -

II. Public POCs for CVE-2021-21425

# POC Description Source Link Shenlong Link
1 GravCMS Unauthenticated Arbitrary YAML Write/Update leads to Code Execution (CVE-2021-21425) https://github.com/CsEnox/CVE-2021-21425 POC Details
2 It is a nmap script for GravCMS vulnerability (CVE-2021-21425) https://github.com/frknktlca/GravCMS_Nmap_Script POC Details
3 working exploit for the old cve-2021-21425 grav cms 1.7.10 vuln https://github.com/bluetoothStrawberry/cve-2021-21425 POC Details
4 It is a nmap script for GravCMS vulnerability (CVE-2021-21425) https://github.com/grey-master-a/GravCMS_Nmap_Script POC Details
5 None https://github.com/afifudinmtop/CVE-2021-21425 POC Details
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III. Intelligence Information for CVE-2021-21425

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Vendor Advisories for CVE-2021-21425 (1)

Exploits & Public PoCs for CVE-2021-21425 (2)

Other References for CVE-2021-21425 (1)

IV. Related Vulnerabilities

Same product: grav-plugin-admin
Same vendor: getgrav
Same weakness: CWE-284

V. Comments for CVE-2021-21425

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