What is the CVSS score of CVE-2019-5421?

CVE-2019-5421 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 1.6%.

Is there a public PoC exploit available for CVE-2019-5421?

Yes, a public proof-of-concept exploit is available for CVE-2019-5421. Prioritise patching immediately. EPSS: 1.6%.

Is there a patch available for CVE-2019-5421?

Yes, a patch is available for CVE-2019-5421. Update the affected software to the latest version immediately.

Devise CVE-2019-5421

CRITICAL

Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)

2019-04-03 support@hackerone.com

Information Disclosure Devise Plataformatec

9.8

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-367 ASVS 5.0 V15 - Secure Coding and Architecture TOCTOU prevention
Impact	CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the critical-severity affected system.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

Patch available 1.6% exploitation probability (EPSS)

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AnalysisAI

Plataformatec Devise version 4.5.0 and earlier, using the lockable module contains a CWE-367 vulnerability in The Devise::Models::Lockable class, more specifically at the. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affected Packages

rubygems devise fix: 4.6.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in rubygems

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-367. Plataformatec Devise version 4.5.0 and earlier, using the lockable module contains a CWE-367 vulnerability in The Devise::Models::Lockable class, more specifically at the #increment_failed_attempts method. File location: lib/devise/models/lockable.rb that can result in Multiple concurrent requests can prevent an attacker from being blocked on brute force attacks. This attack appear to be exploitable via Network connectivity - brute force attacks. This vulnerability appears to have been fixed in 4.6.0 and later. Affected products include: Plataformatec Devise. Version information: version 4.5.0.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

Plataformatec Devise version 4.5.0 and earlier, using the lockable module contains a CWE-367 vulnerability in The Devise::Models::Lockable class, more specifically at the #increment_failed_attempts method. File location: lib/devise/models/lockable.rb that can result in Multiple concurrent requests can prevent an attacker from being blocked on brute force attacks. This attack appear to be exploitable via Network connectivity - brute force attacks. This vulnerability appears to have been fixed in 4.6.0 and later.

Threat Intelligence Overview

EPSS Score

1.6%

Top 28% exploitable

Exploit

POC

Public exploit code exists

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 1.6%

Patch available Yes

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +2

CVSS: +49

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.