CVE-2023-27997

CRITICAL KEV RANSOMWARE

FortiOS/FortiProxy SSL-VPN Heap-based Buffer Overflow

Title source: llm
STIX 2.1

Exploitation Summary

CVE-2023-27997 is actively exploited and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added June 13, 2023, with confirmed use in ransomware campaigns. EIP tracks 12 public exploits from researchers including BishopFox, lexfo, rio128128.

AI-analyzed exploit summary This repository contains a Python-based scanner that detects the presence of CVE-2023-27997, a heap-based buffer overflow in FortiGate SSL VPN, by analyzing response timing differences between valid and invalid requests. It does not exploit the vulnerability but safely identifies vulnerable instances.

Description

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.

Exploits (12)

nomisec SCANNER 134 stars
by BishopFox · infoleak
https://github.com/BishopFox/CVE-2023-27997-check

This repository contains a Python-based scanner that detects the presence of CVE-2023-27997, a heap-based buffer overflow in FortiGate SSL VPN, by analyzing response timing differences between valid and invalid requests. It does not exploit the vulnerability but safely identifies vulnerable instances.

Classification
Scanner 100%
Attack Type
Info Leak
Complexity
Moderate
Reliability
Reliable
Target: FortiGate SSL VPN
No auth needed
Prerequisites: Network access to the target FortiGate SSL VPN instance
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC 65 stars
by lexfo · remote
https://github.com/lexfo/xortigate-cve-2023-27997

This repository contains a functional exploit for CVE-2023-27997, a remote code execution vulnerability in FortiGate SSL VPN. The exploit leverages heap manipulation and MD5-based keystream control to overwrite SSL structs and achieve RCE on ARM32 targets.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Complex
Reliability
Racy
Target: FortiGate SSL VPN (specific firmware undisclosed)
No auth needed
Prerequisites: Network access to vulnerable FortiGate SSL VPN · Python environment with pwntools and ten libraries
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC 27 stars
by rio128128 · remote
https://github.com/rio128128/CVE-2023-27997-POC

This repository contains a functional exploit for CVE-2023-27997, leveraging a buffer overflow vulnerability to achieve remote code execution (RCE) via a crafted HTTP POST request. The exploit uses a ROP chain to execute a reverse shell payload, targeting a specific binary with hardcoded gadgets and addresses.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Complex
Reliability
Reliable
Target: Fortinet FortiOS (specific version not explicitly stated in the code)
No auth needed
Prerequisites: Network access to the target host · Target service (FortiOS) exposed on the specified port
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC 9 stars
by delsploit · remote
https://github.com/delsploit/CVE-2023-27997

This repository contains a functional exploit for CVE-2023-27997, targeting FortiGate VM64 7.2.0. The exploit leverages heap spraying and MD5 hash manipulation to achieve remote code execution (RCE) via a crafted request to the `/remote/hostcheck_validate` endpoint.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Complex
Reliability
Reliable
Target: FortiGate VM64 7.2.0
No auth needed
Prerequisites: Network access to the target FortiGate device · Target running FortiGate VM64 7.2.0
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec SCANNER 2 stars
by TechinsightsPro · poc
https://github.com/TechinsightsPro/ShodanFortiOS

This script uses the Shodan API to search for FortiOS devices vulnerable to CVE-2023-27997 by querying for specific HTTP headers and response patterns. It does not exploit the vulnerability but identifies potentially affected systems.

Classification
Scanner 90%
Attack Type
Info Leak
Complexity
Trivial
Reliability
Reliable
Target: FortiOS
No auth needed
Prerequisites: Shodan API key
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec SCANNER 1 stars
by imbas007 · infoleak
https://github.com/imbas007/CVE-2023-27997-Check

This repository contains a Python script that checks for the presence of CVE-2023-27997, a heap overflow vulnerability in FortiGate SSL VPN, by analyzing response time differences between crafted requests. It does not exploit the vulnerability but detects it through statistical analysis.

Classification
Scanner 95%
Attack Type
Info Leak
Complexity
Moderate
Reliability
Reliable
Target: FortiGate SSL VPN
No auth needed
Prerequisites: Network access to the target FortiGate SSL VPN
devstral-2 · analyzed Feb 18, 2026 Full analysis →
github SCANNER
by dyeat · pythonpoc
https://github.com/dyeat/cve-reproduction/tree/main/Fortinet/FortiOS/CVE-2023-27997

The repository contains a Python script that detects the presence of CVE-2023-27997, a heap-based buffer overflow vulnerability in Fortinet SSL VPN, by analyzing response time differences between crafted requests. It does not exploit the vulnerability but confirms its existence through statistical analysis.

Classification
Scanner 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: Fortinet FortiOS (6.0.x < 6.0.17, 6.2.x < 6.2.15, 6.4.x < 6.4.13, 7.0.x < 7.0.12, 7.2.x < 7.2.5)
No auth needed
Prerequisites: Network access to the target FortiOS SSL VPN interface
devstral-2 · analyzed May 22, 2026 Full analysis →
nomisec SCANNER
by george1-adel · poc
https://github.com/george1-adel/CVE-2023-27997

This repository contains a GitHub Actions-based scanner for CVE-2023-27997, designed to detect vulnerable Fortinet devices by checking domains in batches. It uses Python scripts and tools like httpx/dnsx to identify vulnerable targets but does not include exploit code.

Classification
Scanner 95%
Attack Type
Info Leak
Complexity
Moderate
Reliability
Reliable
Target: Fortinet devices (CVE-2023-27997)
No auth needed
Prerequisites: list of target domains · GitHub Actions environment
devstral-2 · analyzed Apr 10, 2026 Full analysis →
nomisec WORKING POC
by onurkerembozkurt · remote
https://github.com/onurkerembozkurt/fgt-cve-2023-27997-exploit

This repository contains a functional exploit PoC for CVE-2023-27997, a heap-based buffer overflow in FortiGate SSL-VPN that allows unauthenticated remote code execution. The exploit includes a ROP chain and demonstrates the vulnerability by sending a crafted GET request to the '/remote/hostcheck_validate' endpoint.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: FortiOS (7.2.0-7.2.5, 7.0.0-7.0.11, 6.4.0-6.4.12, 6.2.0-6.2.14, 6.0.0-6.0.16)
No auth needed
Prerequisites: Network access to the target FortiGate device · SSL-VPN service exposed on the target
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC
by node011 · remote
https://github.com/node011/CVE-2023-27997-POC

This repository contains a functional exploit for CVE-2023-27997, targeting a heap-based buffer overflow vulnerability in Fortinet FortiOS SSL-VPN. The exploit includes hash calculation, heap spraying, and payload generation to achieve remote code execution.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Complex
Reliability
Reliable
Target: Fortinet FortiOS SSL-VPN
No auth needed
Prerequisites: Network access to vulnerable FortiOS SSL-VPN service · Python environment with required libraries
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC
by puckiestyle · dos
https://github.com/puckiestyle/cve-2023-27997

The PoC demonstrates a DoS vulnerability in Fortinet FortiOS/FortiProxy by sending a large number of crafted POST requests with an oversized payload to the login endpoint, causing resource exhaustion. The exploit uses multiple threads to amplify the attack.

Classification
Working Poc 90%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Fortinet FortiOS/FortiProxy
No auth needed
Prerequisites: Network access to the target device
devstral-2 · analyzed Feb 18, 2026 Full analysis →

Scores

CVSS v3 9.8
EPSS 0.9085
EPSS Percentile 99.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation active
Automatable yes
Technical Impact total

Details

CISA KEV 2023-06-13
VulnCheck KEV 2023-06-12
InTheWild.io 2023-06-13
ENISA EUVD EUVD-2023-31722
Ransomware Use Confirmed
CWE
CWE-122 CWE-787
Status published
Products (13)
fortinet/fortios 6.0.10
fortinet/fortios 6.2.4
fortinet/fortios 6.2.6
fortinet/fortios 6.2.7
fortinet/fortios 6.4.2
fortinet/fortios 6.4.6
fortinet/fortios 6.4.8
fortinet/fortios 6.4.10
fortinet/fortios 6.4.12
fortinet/fortios 7.0.5
... and 3 more
Published Jun 13, 2023
KEV Added Jun 13, 2023
Tracked Since Feb 18, 2026