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Fortios CVE-2023-27997

CRITICAL
Heap-based Buffer Overflow (CWE-122)
2023-06-13 psirt@fortinet.com
9.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

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.

Emergency Immediate action required. Why: CRITICAL + in CISA KEV (actively exploited), no patch available.
Exploited in the wild (CISA KEV) No patch listed yet 85.7% exploitation probability (EPSS)

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AnalysisAI

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and. Rated critical severity (CVSS 9.8), 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. 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-122. A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests. Affected products include: Fortinet Fortiproxy, Fortinet Fortios. Version information: version 7.2.4.

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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

Lifecycle Timeline

2
Added to CISA KEV
Jul 14, 2026 - 04:22 CISA
CVE Published
Jun 13, 2023 - 09:15 nvd
CRITICAL 9.8

DescriptionNVD

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

Threat Intelligence Overview

Threat Score
6.0/10
Composite threat intelligence
EPSS Score
85.7%
Top 0% exploitable
EUVD KEV
Listed
EU Exploited Vulnerability
Data Quality
5 sources
Confidence: Medium

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 Yes
Public POC No
EPSS 85.7%
Patch available No
Active threat Yes
Deciding rule
CRITICAL + in CISA KEV (actively exploited), no patch 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
Immediate
Exploitation· derived
Active
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
High

Priority Score

185
Low Medium High Critical
KEV: +50
EPSS: +86
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)NVD

cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.0.10:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.2.4:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.2.6:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.2.7:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.4.2:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.4.6:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.4.8:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:6.4.10:*:*:*:*:*:*:*
+ 3 more
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CVE-2025-25249 CRITICAL POC
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Remote code execution in Fortinet FortiOS (6.4 through 7.6.3) and FortiSwitchManager (7.0.x/7.2.x) lets an attacker run

CVE-2025-61624 MEDIUM POC
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Path traversal vulnerability in Fortinet FortiOS, FortiProxy, FortiPAM, and FortiSwitchManager allows authenticated admi

CVE-2015-1880 MEDIUM POC
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CVE-2025-24472 HIGH
8.1 Feb 11

FortiOS and FortiProxy contain an authentication bypass allowing unauthenticated attackers with knowledge of upstream/do

CVE-2025-68686 MEDIUM POC
5.9 Feb 10

An Exposure of Sensitive Information to an Unauthorized Actor vulnerability [CWE-200] vulnerability in Fortinet FortiOS

CVE-2019-6693 MEDIUM
6.5 Nov 21

Use of a hard-coded cryptographic key to cipher sensitive data in FortiOS configuration backup file may allow an attacke

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