CVE-2021-21425
Unauthenticated Arbitrary YAML Write/Update leads to Code Execution
Public exploit available. Not confirmed exploited in the wild yet. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
3 sources with a proof of concept or module.
Exploit links, PoCs and Metasploit modules after sign-in- EPSS
81% chance of exploitation activity in the next 30 days, which ranks it in the 99th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
5 events over 1902 days, from the signal feeds we watch.
- EPSS band changecritical → high
- Public exploit / PoCsource: other
- Record updated
- Publishedweakness classified
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
Scored 9.3 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability NoneNo availability impact
Weaknesses
Sources
References in the record
- 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
And 1 more reference. See all after sign-in
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