What is the CVSS score of CVE-2021-3637?

CVE-2021-3637 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 1.1%.

Is there a patch available for CVE-2021-3637?

Yes, a patch is available for CVE-2021-3637. Update the affected software to the latest version immediately.

Keycloak CVE-2021-3637

HIGH

Allocation of Resources Without Limits or Throttling (CWE-770)

2021-07-09 secalert@redhat.com

Denial Of Service Red Hat Keycloak Single Sign On

7.5

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-770 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V2 - Validation and Business Logic Resource allocation limits MITRE ATT&CK 1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could exhaust system resources through uncontrolled allocation by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 1.1% exploitation probability (EPSS)

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AnalysisAI

A flaw was found in keycloak-model-infinispan in keycloak versions before 14.0.0 where authenticationSessions map in RootAuthenticationSessionEntity grows boundlessly which could lead to a DoS attack. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Set resource limits, implement rate limiting, validate input sizes.

Affected Packages

maven org.keycloak:keycloak-model-infinispan fix: 14.0.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in maven

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 as Allocation of Resources Without Limits (CWE-770), which allows attackers to exhaust system resources through uncontrolled allocation. A flaw was found in keycloak-model-infinispan in keycloak versions before 14.0.0 where authenticationSessions map in RootAuthenticationSessionEntity grows boundlessly which could lead to a DoS attack. Affected products include: Redhat Keycloak, Redhat Single Sign-On. Version information: before 14.0.0.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH

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

None

Integrity

None

Availability

High

DescriptionNVD

Threat Intelligence Overview

EPSS Score

1.1%

Top 37% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

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 HIGH

CISA KEV No

Public POC No

EPSS 1.1%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

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

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +38

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:redhat:keycloak:*:*:*:*:*:*:*:*

cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*

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References

Advisories & patches

ADVISORY https://bugzilla.redhat.com/show_bug.cgi?id=1979638

Search Externally

GitHub PoC

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