Threats / Fortinet / CVE-2023-27997
CVE-2023-27997
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Fortinet FortiOS and FortiProxy SSL-VPN vulnerability
Fortinet FortiOS and FortiProxy SSL-VPN contain a heap-based buffer overflow allowing unauthenticated remote code execution. Actively exploited in ransomware campaigns.
Verdict
Today item, not a backlog item.
Critical remote code execution vulnerability in widely deployed VPN appliances. No authentication required. High exploitation prevalence in ransomware operations indicates immediate risk to exposed instances.
CISA KEV Yes · 2023-06-133Ransomware use Flagged3EPSS 0.85689 (verify live)4Exploit Weaponized · public PoC5
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
42 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-13), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.85689 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Fortinet, FortiOS and FortiProxy SSL-VPN. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-122 Heap-based Buffer Overflow — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft malicious SSL-VPN requests designed to overflow heap memory and inject executable code.
Business
Attackers gain unauthenticated remote code execution on perimeter security appliances, establishing initial network access.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute commands with appliance privileges to establish persistence and lateral movement capabilities.
Business
Compromised VPN gateways become pivot points for internal network reconnaissance and credential harvesting.
3
Lateral reach — past segmentation narrative 3
Attacker
I deploy ransomware payloads across the internal network using the compromised appliance as distribution vector.
Business
Ransomware operators encrypt critical systems and demand payment, disrupting operations and threatening data confidentiality.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05