What is the CVSS score of CVE-2020-12676?

CVE-2020-12676 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 2.9%.

Is there a public PoC exploit available for CVE-2020-12676?

Yes, a public proof-of-concept exploit is available for CVE-2020-12676. Prioritise patching immediately. EPSS: 2.9%.

Fusionauth CVE-2020-12676

CRITICAL

Improper Verification of Cryptographic Signature (CWE-347)

2020-10-02 cve@mitre.org

Denial Of Service Jwt Attack Fusionauth Samlv2

9.1

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-347 OWASP Top 10:2025 A04:2025 - Cryptographic Failures ASVS 5.0 V11 - Cryptography Signature verification
Impact	CVSS score of 9.1 (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.

No patch listed yet 2.9% exploitation probability (EPSS)

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AnalysisAI

FusionAuth fusionauth-samlv2 0.2.3 allows remote attackers to forge messages and bypass authentication via a SAML assertion that lacks a Signature element, aka a "Signature exclusion attack". Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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-347. FusionAuth fusionauth-samlv2 0.2.3 allows remote attackers to forge messages and bypass authentication via a SAML assertion that lacks a Signature element, aka a "Signature exclusion attack". Affected products include: Fusionauth Samlv2.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.1 CRITICAL

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

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

None

DescriptionNVD

FusionAuth fusionauth-samlv2 0.2.3 allows remote attackers to forge messages and bypass authentication via a SAML assertion that lacks a Signature element, aka a "Signature exclusion attack".

Threat Intelligence Overview

EPSS Score

2.9%

Top 15% 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 2.9%

Patch available No

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.