CVE-2021-21425

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 80.6%, top 0% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this weekWeaponized
9.3
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 81%
CISA-KEV: Not listedEPSS: 81%CVSS: 9.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
79(Track*)
EG Risk 79/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity93% × 45%
Exploitation81% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
99.6%
KEV
Not listed

Published

April 7, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Jul 17, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic🟡 PoC Available

Unexpected Journey #7 – GravCMS Unauthenticated Arbitrary YAML Write/Update leads to Code Execution (CVE-2021-21425) – Pentest Blog

https://pentest.blog/unexpected-journey-7-gravcms-unauthenticated-arbitrary-yaml-write-update-leads-to-code-execution/
github Patch Available

Unauthenticated Arbitrary YAML Write/Update leads to Code Execution · Advisory · getgrav/grav-plugin-admin · GitHub

https://github.com/getgrav/grav-plugin-admin/security/advisories/GHSA-6f53-6qgv-39pj

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 24× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 01:57 UTCEG score recompute
  3. 2026-07-22 22:43 UTCEG score recompute
  4. 2026-07-22 14:05 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
  6. 2026-07-18 22:59 UTCOSV refresh
  7. 2026-07-16 17:00 UTCEPSS rescore
  8. 2026-07-15 16:55 UTCEPSS rescore
  9. 2026-07-15 16:55 UTCEPSS rescore
  10. 2026-07-12 05:44 UTCEPSS rescore
  11. 2026-07-12 05:44 UTCEPSS rescore
  12. 2026-07-09 19:07 UTCEPSS rescore
  13. 2026-07-08 15:12 UTCEPSS rescore
  14. 2026-07-04 06:29 UTCEPSS rescore
  15. 2026-07-04 06:29 UTCEPSS rescore
  16. 2026-07-01 15:03 UTCEPSS rescore
  17. 2026-07-01 05:48 UTCOSV refresh
  18. 2026-06-29 14:04 UTCEPSS rescore
  19. 2026-06-29 14:04 UTCEPSS rescore
  20. 2026-06-28 14:05 UTCEPSS rescore
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-28 04:54 UTCEPSS rescore
  23. 2026-06-25 13:48 UTCEPSS rescore
  24. 2026-06-25 13:48 UTCEPSS rescore
  25. 2026-06-24 14:03 UTCEPSS rescore
Show 31 more
  1. 2026-06-24 14:03 UTCEPSS rescore
  2. 2026-06-23 21:31 UTCEPSS rescore
  3. 2026-06-23 21:31 UTCEPSS rescore
  4. 2026-06-21 01:58 UTCEPSS rescore
  5. 2026-06-21 01:57 UTCEPSS rescore
  6. 2026-06-19 19:24 UTCEPSS rescore
  7. 2026-06-19 19:24 UTCEPSS rescore
  8. 2026-06-17 17:51 UTCEPSS rescore
  9. 2026-06-15 17:46 UTCEPSS rescore
  10. 2026-06-14 23:15 UTCEPSS rescore
  11. 2026-06-13 09:43 UTCOSV refresh
  12. 2026-06-12 23:10 UTCEPSS rescore
  13. 2026-06-12 23:10 UTCEPSS rescore
  14. 2026-06-10 22:16 UTCEPSS rescore
  15. 2026-06-10 22:16 UTCEPSS rescore
  16. 2026-06-10 13:20 UTCEPSS rescore
  17. 2026-06-06 13:46 UTCEPSS rescore
  18. 2026-06-06 13:46 UTCEPSS rescore
  19. 2026-06-06 13:46 UTCEPSS rescore
  20. 2026-06-05 22:45 UTCEPSS rescore
  21. 2026-06-05 22:45 UTCEPSS rescore
  22. 2026-06-05 06:09 UTCEPSS rescore
  23. 2026-06-05 06:09 UTCEPSS rescore
  24. 2026-06-05 06:08 UTCEPSS rescore
  25. 2026-06-01 13:50 UTCEPSS rescore
  26. 2026-06-01 13:50 UTCEPSS rescore
  27. 2026-05-28 13:43 UTCEPSS rescore
  28. 2026-05-28 13:43 UTCEPSS rescore
  29. 2026-05-26 18:37 UTCEG score recompute
  30. 2026-05-26 13:42 UTCEPSS rescore
  31. 2026-05-26 13:42 UTCEPSS rescore

Publicly available exploits

(4 references)

Working exploit code is in the public domain (1 Metasploit module) (2 GitHub PoCs) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCbluetoothStrawberry/cve-2021-21425
    First seen Nov 13, 2024

    working exploit for the old cve-2021-21425 grav cms 1.7.10 vuln

    Open source ↗
  • GitHub PoCCsEnox/CVE-2021-21425
    First seen Jun 24, 2021

    GravCMS Unauthenticated Arbitrary YAML Write/Update leads to Code Execution (CVE-2021-21425)

    Open source ↗
  • Exploit-DBEDB-49788✓ verified
    First seen Apr 21, 2021

    GravCMS 1.10.7 - Unauthenticated Arbitrary File Write (Metasploit)

    Open source ↗
  • Metasploitexploit/linux/http/gravcms_exec✓ verified
    First seen Mar 29, 2021

    GravCMS Remote Command Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-21425?
CVE-2021-21425 is a critical vulnerability published on April 7, 2021. 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…
When was CVE-2021-21425 disclosed?
CVE-2021-21425 was first published in the National Vulnerability Database on April 7, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-21425 actively exploited?
CVE-2021-21425 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-21425?
CVE-2021-21425 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2021-21425?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21425, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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