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Fortiweb CVE-2021-41025

CRITICAL
Race Condition (CWE-362)
2021-12-08 psirt@fortinet.com
9.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Concurrency control, locking
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.

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.
Patch available 1.4% exploitation probability (EPSS)

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AnalysisAI

Multiple vulnerabilities in the authentication mechanism of confd in FortiWeb versions 6.4.1, 6.4.0, 6.3.0 through 6.3.15, 6.2.0 through 6.2.6, 6.1.0 through 6.1.2, 6.0.0 thorugh 6.0.7, including an. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

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.

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-362. Multiple vulnerabilities in the authentication mechanism of confd in FortiWeb versions 6.4.1, 6.4.0, 6.3.0 through 6.3.15, 6.2.0 through 6.2.6, 6.1.0 through 6.1.2, 6.0.0 thorugh 6.0.7, including an instance of concurrent execution using shared resource with improper synchronization and one of authentication bypass by capture-replay, may allow a remote unauthenticated attacker to circumvent the authentication process and authenticate as a legitimate cluster peer. Affected products include: Fortinet Fortiweb. Version information: through 6.3.15.

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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

Multiple vulnerabilities in the authentication mechanism of confd in FortiWeb versions 6.4.1, 6.4.0, 6.3.0 through 6.3.15, 6.2.0 through 6.2.6, 6.1.0 through 6.1.2, 6.0.0 thorugh 6.0.7, including an instance of concurrent execution using shared resource with improper synchronization and one of authentication bypass by capture-replay, may allow a remote unauthenticated attacker to circumvent the authentication process and authenticate as a legitimate cluster peer.

Threat Intelligence Overview

EPSS Score
1.4%
Top 30% exploitable
Data Quality
2 sources
Confidence: Low

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 No
EPSS 1.4%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
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

50
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).

Affected Products (CPE)NVD

cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.1.0:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.1.1:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.1.2:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.0:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.1:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.2:*:*:*:*:*:*:*
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CVE-2024-48885 CRITICAL
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CVE-2016-4066 HIGH
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Cross-site request forgery (CSRF) vulnerability in Fortinet FortiWeb before 5.5.3 allows remote attackers to hijack the

CVE-2024-23665 HIGH
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