CVE-2019-5420

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because EPSS predicts 94% probability of exploitation within the next 30 days (top 0.1% of all CVEs). NVD baseline CVSS 9.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Weaponized
9.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 92%
CISA-KEV: Not listedEPSS: 92%CVSS: 9.8Exploit: NoneExposed: 0

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

A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow an attacker to guess the automatically generated development mode secret token. This secret token can be used in combination with other Rails internals to escalate to a remote code execution exploit.

CVSS v3
9.8
EG Score
9.8(high)
EPSS
99.8%
KEV
Not listed

Published

March 27, 2019

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated Jul 7, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

Ruby On Rails - DoubleTap Development Mode secret_key_base Remote Code Execution (Metasploit) - Linux remote Exploit

https://www.exploit-db.com/exploits/46785/
generic

[SECURITY] Fedora 30 Update: rubygem-activemodel-5.2.3-2.fc30 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/
generic

Redirecting to Google Groups

https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
generic

Packet Storm

http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.html

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
railties5.2.0 ... 5.2.2.rc1 (6 versions)5.2.2.1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 3× in last 7d / 14× 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. 2026-07-07 13:43 UTCEPSS rescore
  2. 2026-07-06 16:25 UTCEPSS rescore
  3. 2026-07-06 16:25 UTCEPSS rescore
  4. 2026-07-04 06:28 UTCEPSS rescore
  5. 2026-07-03 14:56 UTCOSV refresh
  6. 2026-06-24 14:03 UTCEPSS rescore
  7. 2026-06-24 14:03 UTCEPSS rescore
  8. 2026-06-23 21:31 UTCEPSS rescore
  9. 2026-06-23 21:31 UTCEPSS rescore
  10. 2026-06-16 17:50 UTCEPSS rescore
  11. 2026-06-15 17:46 UTCEPSS rescore
  12. 2026-06-15 04:43 UTCOSV refresh
  13. 2026-06-12 23:09 UTCEPSS rescore
  14. 2026-06-12 23:09 UTCEPSS rescore
  15. 2026-06-11 13:58 UTCEPSS rescore
  16. 2026-06-10 13:19 UTCEPSS rescore
  17. 2026-06-05 06:08 UTCEPSS rescore
  18. 2026-06-04 13:10 UTCEPSS rescore
  19. 2026-06-04 13:10 UTCEPSS rescore
  20. 2026-06-02 20:11 UTCEPSS rescore
  21. 2026-06-02 20:11 UTCEPSS rescore
  22. 2026-06-01 13:50 UTCEPSS rescore
  23. 2026-06-01 13:50 UTCEPSS rescore
  24. 2026-05-31 22:29 UTCEPSS rescore
  25. 2026-05-31 22:29 UTCEPSS rescore
Show 6 more
  1. 2026-05-29 13:42 UTCEPSS rescore
  2. 2026-05-27 21:22 UTCEG score recompute
  3. 2026-05-26 07:17 UTCEPSS rescore
  4. 2026-05-26 07:17 UTCEPSS rescore
  5. 2026-05-26 07:17 UTCEPSS rescore
  6. 2026-05-24 16:47 UTCEPSS rescore

Publicly available exploits

(6 references)

Working exploit code is in the public domain (1 Metasploit module) (4 GitHub PoCs) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoClaffray/ruby-RCE-CVE-2019-5420-
    First seen Jul 2, 2022

    Ruby反序列化命令执行漏洞（CVE-2019-5420）-vulfocus通关版

    Open source ↗
  • GitHub PoCj4k0m/CVE-2019-5420
    First seen Sep 6, 2021

    A vulnerability can allow an attacker to guess the automatically generated development mode secret token.

    Open source ↗
  • GitHub PoCscumdestroy/CVE-2019-5420.rb
    First seen May 11, 2021

    POC Exploit written in Ruby

    Open source ↗
  • Exploit-DBEDB-46785✓ verified
    First seen May 2, 2019

    Ruby On Rails - DoubleTap Development Mode secret_key_base Remote Code Execution (Metasploit)

    Open source ↗
  • GitHub PoCknqyf263/CVE-2019-5420
    First seen Mar 21, 2019

    CVE-2019-5420 (Ruby on Rails)

    Open source ↗
  • Metasploitexploit/multi/http/rails_double_tap✓ verified
    First seen Mar 13, 2019

    Ruby On Rails DoubleTap Development Mode secret_key_base Vulnerability

    Open source ↗

Frequently asked(5)

What is CVE-2019-5420?
CVE-2019-5420 is a critical vulnerability published on March 27, 2019. A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow an attacker to guess the automatically generated development mode secret token. This secret token can be used in combination with other Rails internals to escalate to a remote code execution exploit.
When was CVE-2019-5420 disclosed?
CVE-2019-5420 was first published in the National Vulnerability Database on March 27, 2019, 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-2019-5420 actively exploited?
CVE-2019-5420 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2019-5420?
CVE-2019-5420 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2019-5420?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2019-5420, 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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