CVE-2021-21425
CriticalPublic exploitIn versions 1.10.7 and earlier, an unauthenticated user can execute some methods of administrator controller without needing any credentials.
Published Apr 7, 2021 · Updated Aug 7, 2026 · Also known as GHSA-6f53-6qgv-39pj
Key Facts
Patch immediately- CVE-2021-21425 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Grav-Plugin-Admin (Getgrav).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 81% probability of exploitation in the next 30 days.
- Fixed versions are available, including Grav-Plugin-Admin 1.10.8.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
81%
Higher than 99.6% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-21425 brief as a PDF
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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.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Grav-Plugin-AdminGetgrav | >= <= 1.10.7 | 1.10.8 |
Patched Releases
Grav-Plugin-Admin
1.10.8
Timeline
Publicly disclosed
Apr 7, 2021
Last updated
Aug 7, 2026
Weakness Type
- CWE-284 Improper Access Control
References
- advisoryhttp://packetstormsecurity.com/files/162283/GravCMS-1.10.7-Remote-Command-Execution.html
- advisoryhttp://packetstormsecurity.com/files/162457/GravCMS-1.10.7-Remote-Command-Execution.html
- advisoryhttps://github.com/getgrav/grav-plugin-admin/security/advisories/GHSA-6f53-6qgv-39pj
- exploitMSF gravcms_exec.rb
- exploithttps://pentest.blog/unexpected-journey-7-gravcms-unauthenticated-arbitrary-yaml-write-update-leads-to-code-execution/
FAQ
Common Questions.
Grav Admin Plugin is an HTML user interface that provides a way to configure Grav and create and modify pages.
Affected: Grav-Plugin-Admin (Getgrav) versions >= <= 1.10.7. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Grav-Plugin-Admin 1.10.8.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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