CVE-2023-27997

Exploitation: active CVSS 9.2 CRITICAL Ransomware: known use

CVSS base score: 9.2 (Critical) vendor CNA · v3.1

Score assigned by the vendor's own CVE Numbering Authority (CNA); CISA's Vulnrichment program adds a score only when the CNA omits one.

Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability

Vendor: Fortinet Product: FortiOS and FortiProxy SSL-VPN

Description

Fortinet FortiOS and FortiProxy SSL-VPN contain a heap-based buffer overflow vulnerability which can allow an unauthenticated, remote attacker to execute code or commands via specifically crafted requests.

Lifecycle Timeline

2023-06-13

CVE published

Entered the public CVE record.

CVE.org →
2023-06-13

Added to CISA KEV

Listed as known exploited, which starts the federal remediation clock.

CISA KEV →
2023-06-16

Public exploit code 3 days later

Public GitHub repository BishopFox/CVE-2023-27997-check — unvetted, may contain malware

GitHub PoC →
2023-07-04

Federal remediation due 18 days later

Deadline for federal civilian agencies under BOD 22-01 — now passed.

CISA KEV
2023-07-08

EPSS flags exploitation risk 4 days later

Probability rose past 10%, from 5.7% to 15.4%. Dated to the sampled week.

FIRST EPSS →
2024-07-25

First national advisory 13 months later

NSA — North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs

CyberzSOC advisory index →
not recorded

Vendor fix published

No dated vendor fix. Only Microsoft publishes a machine-readable release date; other vendors state a fixed version without one.

Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 183 points from 2023-06-17, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 92.4% on 2026-05-23.

Published Applicability

CVE List v5 (CNA container) 22 affected · 0 fixed · 0 not affected

Check whether a specific version is affected →

What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.

Research & News Coverage

No mentions found in monitored research blogs or news feeds.

Detection & Exploitation

Scan

none published

Exploit / Pen Test

GitHub PoC12

Network IDS/IPS

Snort (ET Open)7 Suricata (ET Open)7

Host / SIEM

Sigma

Coverage across public collections only: Nuclei and OpenVAS NVT (scan); Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM); Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by PoC-in-GitHub (CC0) and are not vetted: some are fakes and some are malware. Treat them as evidence that code was published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available under the Open Database License (ODbL) v1.0; its individual Vulnerability Tests are licensed GNU GPL v2.

CISA Assessment (Vulnrichment / SSVC)

Exploitation

active

Automatable

yes

Technical impact

total

CVSS — CISA

—

CVSS — vendor CNA 3.1

9.2 CRITICAL

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:X/RC:R

Weakness

CWE-122 — Execute unauthorized code or commands

Assessment updated

2024-10-23

D3FEND Countermeasures

Defensive techniques inferred by MITRE D3FEND from the underlying weakness (CWE-122) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.

Model

Asset Vulnerability Enumeration Software Inventory

Harden

Credential Scrubbing Domain Logic Validation Software Update Trusted Library Variable Initialization

Isolate

Application-based Process Isolation

Restore

Restore Software

KEV Catalog Status

Added to KEV

2023-06-13

BOD 22-01 due date

2023-07-04

Known ransomware use

Known

Listed By

Source	Date	Record
CISA KEV	2023-06-13	source record →
CISA Vulnrichment	2024-10-23	source record →

Referenced in Advisories

Date	Advisory	Issuer
2025-04-11	Fortinet Releases Advisory on New Post-Exploitation Technique for Known Vulnerabilities	CISA
2025-01-28	A method to assess 'forgivable' vs 'unforgivable' vulnerabilities	NCSC
2024-11-12	2023 Top Routinely Exploited Vulnerabilities	CISA
2024-09-18	People's Republic of China-Linked Actors Compromise Routers and IoT Devices for Botnet Operations	FBI
2024-08-29	#StopRansomware: RansomHub Ransomware	CISA
2024-07-25	North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs	NSA
2024-07-25	North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime's Military and Nuclear Programs	NSA

Weaponization Timeline — Offensive & Testing Tools

No exploit-tool sightings recorded for this CVE.

Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.

External References

CVE.org record → NVD entry → CISA KEV catalog → FortiGuard Labs → Rapid7 AttackerKB →

⚠ Known Exploited Vulnerability (KEV) Tracker