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CVE-2023-27997

Published: Jun 13, 2023Updated: Jul 31, 2026 Sources: CVE List NVD BDU csafCWE-122
9.8CRITICAL
NVD MITRE
EPSS Score
85.7%
Top 0.3%
CISA KEV
Active Exploitation
Since Jun 13, 2023
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Nuclei · OpenVAS

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.

In plain language

AI Act now

CVE-2023-27997 is a critical SSL-VPN security flaw in FortiOS and FortiProxy that lets attackers run code over the network without needing a login; if your FortiOS/FortiProxy appliance has SSL-VPN reachable from the internet, you should act now.

Executive summary

CVE-2023-27997 is an unauthenticated remote code execution flaw in FortiOS SSL-VPN (and FortiProxy), caused by a heap-based buffer overflow triggered by specially crafted network requests; it is listed in CISA KEV as exploited in ransomware campaigns.

If affected, business impact
Full device compromiseRansomware riskService outageData theft

What to do now

  1. Check whether your FortiOS/FortiProxy device is running one of these affected versions: FortiOS 7.2.4 and below, 7.0.11 and below, 6.4.12 and below, 6.0.16 and below; and FortiProxy 7.2.3 and below.
  2. Check whether SSL-VPN is enabled and reachable from untrusted networks (for example, the public internet).
  3. Upgrade to the fixed versions per vendor guidance: FortiOS 6K7K to 7.0.12 or above, 6.4.13 or above, 6.2.15 or above, or 6.0.17 or above.
  4. If you cannot upgrade immediately, disable SSL-VPN exposure and restrict access so it is not reachable from the internet, then schedule the upgrade as soon as possible.
Patch / advisory Some work to apply

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-122CWE-787

Affected Products

Fortinet
commercial·USaka forti net
FortiProxy
Security Products
FortiOS
Security Products
FortiOS-6K7K
Security Products
Fortinet Inc.
commercial·USaka fortinet
FortiOS-6K7K
Security Products
FortiProxy
Security Products
FortiOS
Security Products
and 2 more affected products View all →

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Jun 13, 2023
Remediation due:Jul 4, 2023
Ransomware:Known ransomware use

Required action: Apply updates per vendor instructions.

Official Patch Available
Is your org exposed to CVE-2023-27997?We'll check your whole external perimeter for exposure — free. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://fortiguard.com/psirt/FG-IR-23-097
fortiguard.com
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27997
cisa.gov
https://www.fortiguard.com/psirt/FG-IR-23-097
fortiguard.com
and 87 more references View all →
News mentions
3

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