CVE-2019-5420

Name: CVE-2019-5420
Creator: NVD / NIST
Published: 2019-03-27T14:29:01.72+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 92.14%

Last modified Jun 17, 2026

CVE-2019-5420 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 92.14% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

92.14%

99.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Rubyonrails	Rails	< 5.2.2.1	—
Rubyonrails	Rails	6.0.0	Beta1
Debian	Debian Linux	8.0	—
Fedoraproject	Fedora	30	—

References

http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/
https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/Patch, Vendor Advisory
https://www.exploit-db.com/exploits/46785/Exploit, Third Party Advisory, VDB Entry
http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/
https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/Patch, Vendor Advisory
https://www.exploit-db.com/exploits/46785/Exploit, Third Party Advisory, VDB Entry

Timeline

Published: Mar 27, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-5420?

How severe is CVE-2019-5420?

CVE-2019-5420 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 92.14% probability of exploitation in the next 30 days.

How do I fix CVE-2019-5420?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-5420?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST