CVE-2019-5420

Exp

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.

Published: 2019-03-27 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-5420 is rated High Exploit Risk (88.9/100): CVSS Critical severity, with high exploitation likelihood (EPSS 93.51%, 100th percentile). 3 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2019-5420

EDB-ID Source Kind Published Link
46785 exploit_db edb 2019-05-02 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2019-5420

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-03 93.75% 93.51% -0.23%
2 2026-03-21 93.10% 93.75% +0.64%
3 2026-01-16 — 93.10% —

Full EPSS history (40 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-5420

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2019-5420

GitHub Security Advisory for CVE-2019-5420

GHSA-m42h-mh85-4qgc · Severity: critical · Ecosystem: rubygems — Use of Insufficiently Random Values in Railties Allows Remote Code Execution

OS Trackers for CVE-2019-5420

vendor priority summary link
debian not yet assigned CVE-2019-5420 not yet assigned priority: Debian including 1 source packages (rails), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-5420
redhat medium — https://access.redhat.com/security/cve/CVE-2019-5420
suse high CVE-2019-5420 severity important: SUSE including 36 source package names (rmt-server-2.21-150700.1.21, rmt-server-2.6.13-1.1, …), 64 product×package rows across 32 product lines (SUSE Enterprise Storage 4, SUSE Lifecycle Management Server 1.3, … (32 product lines)): Fixed 33, Known Not Affected 31. https://www.suse.com/security/cve/CVE-2019-5420/
ubuntu medium CVE-2019-5420 medium priority: Ubuntu including 7 source packages (rails, rails-4.0, …), 49 status rows across 7 suites (bionic, cosmic, disco, eoan, trusty, upstream, xenial): DNE 37, needs-triage 7, not-affected 3, ignored 2. https://ubuntu.com/security/CVE-2019-5420

Affected software / configurations for CVE-2019-5420

Vendor Product Version Raw CPE
rubyonrails rails < 5.2.2.1 cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*
rubyonrails rails 6.0.0 cpe:2.3:a:rubyonrails:rails:6.0.0:beta1:*:*:*:*:*:*
rubyonrails rails 6.0.0 cpe:2.3:a:rubyonrails:rails:6.0.0:beta2:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
fedoraproject fedora 30 cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*

References for CVE-2019-5420

cvelogic Threat Intelligence