Skip to content
Fencer Vulns
critical 9.8

CVE-2019-5420 in the critical feed json

Use of Insufficiently Random Values in Railties Allows Remote Code Execution

published 2019-03-13 7 y ago modified 2026-06-17 4 mo ago also GHSA-m42h-mh85-4qgc , EUVD-2019-0385

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
89.3%
EPSS 89.3% chance of exploitation in 30 days, percentile 99.7%
public exploits
2
Metasploit, Exploit-DB

Summary

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.

Patch / fix

  • rubygems railties 5.2.2.1
  • rubyonrails rails 5.2.2.1
  • rails Debian 14, Debian 13, Debian 12 2:5.2.2.1+dfsg-1

debian advisories DEBIAN-CVE-2019-5420

  • rmt-server SLE Module for Server Applications 15 SP1, SLE Module for Public Cloud 15 SP1 2.6.5-3.18.1
  • rmt-server SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.6.5-3.34.1
  • rmt-server SLE Module for Server Applications 15 SP2, SLE Module for Public Cloud 15 SP2 2.6.5-3.3.1

suse advisories SUSE-SU-2020:3160-1SUSE-SU-2020:3147-1SUSE-SU-2020:3036-1

  • rmt-server openSUSE Tumbleweed 2.6.13-1.1
  • rmt-server openSUSE Leap 15.1 2.6.5-lp151.2.18.2
  • rmt-server openSUSE Leap 15.2 2.6.5-lp152.2.3.1

opensuse advisories openSUSE-SU-2024:10589-1openSUSE-SU-2020:2000-1openSUSE-SU-2020:1993-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-5420 updated cvss 8.1

rubygem-rails: Weak secret token leading to possible code execution

  • Red Hat Software Collections rh-ror42-rubygem-rails, rh-ror50-rubygem-rails
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (Metasploit exploit/multi/http/rails_double_tap)
  2. Published

Exploit prediction

89.33% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Metasploit exploit/multi/http/rails_double_tap Ruby On Rails DoubleTap Development Mode secret_key_base Vulnerability metasploit exploit, excellent rank, 2019-03-13
  • EDB-46785 Ruby On Rails - DoubleTap Development Mode secret_key_base Remote Code Execution (Metasploit) remote, 2019-05-02
  • packetstormsecurity.com http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.0 9.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
rubygems railties
>=5.2.0, <5.2.2.1
5.2.2.1

Affected products

  • Rails https://github.com/rails/rails

Classification

Weakness
  • CWE-77 Improper Neutralization of Special Elements used in a Command
  • CWE-330 Use of Insufficiently Random Values
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.