CVE-2021-21425
Unauthenticated Arbitrary YAML Write/Update leads to Code Execution
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
9.3
Unauthenticated Arbitrary YAML Write/Update leads to Code Execution
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.
- Record
CVE-2021-21425- CVSS 3.1
- 9.3 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
EUVDEUVD-2021-8706
9.3
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.
- Record
EUVD-2021-8706- CVSS 3.1
- 9.3 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N - Updated
- 2026-11-03
NVD
9.3
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.
- Record
CVE-2021-21425- CVSS 3.1
- 9.3 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-284
- Updated
- 2026-11-02
OSV
9.8
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.
- Record
CVE-2021-21425- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| Exploit-DB | GravCMS 1.10.7 - Unauthenticated Arbitrary File Write (Metasploit) | 2021-04-21 |
| Metasploit | GravCMS Remote Command Execution | 2021-03-29 |
| PoC in GitHub | CsEnox/CVE-2021-21425 | 2021-06-24 |
| PoC in GitHub | afifudinmtop/CVE-2021-21425 | 2026-01-21 |
| PoC in GitHub | bluetoothStrawberry/cve-2021-21425 | 2024-11-13 |
| PoC in GitHub | d4ytox/CVE-2021-21425 | 2026-06-13 |
| PoC in GitHub | grey-master-a/GravCMS_Nmap_Script | 2022-01-19 |
| PoC in GitHub | s1lentf00thold/CVE-2021-21425-RCE | 2026-06-23 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, Exploit-DB, Metasploit, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21425 is a critical vulnerability (CVSS 9.3) in Getgrav Grav-plugin-admin, published April 7, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 80.6%, the 99th percentile. No source names a fixed version.
References
pentest.blog/unexpected-journey-7-gravcms-unauthenticated-arbitrary-yaml-write-update-leads-to-code-execution
github.com/getgrav/grav-plugin-admin/security/advisories/GHSA-6f53-6qgv-39pj
packetstormsecurity.com/files/162283/GravCMS-1.10.7-Remote-Command-Execution.html
packetstormsecurity.com/files/162457/GravCMS-1.10.7-Remote-Command-Execution.html