Is CVE-2023-27997 in the CISA KEV catalog?

Yes. CVE-2023-27997 is on the CISA Known Exploited Vulnerabilities list, added 2023-06-13, and has known ransomware campaign use.

What is the CVSS severity of CVE-2023-27997?

CVE-2023-27997 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2023-27997?

CVE-2023-27997 has an EPSS score of 85.69% (100th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2023-27997?

No published fix for CVE-2023-27997 has been found yet. It is on the CISA Known Exploited Vulnerabilities list; federal agencies must remediate by 2023-07-04. Apply the vendor's mitigations per CISA's guidance.

CVE & CISA-KEV Catalog

CVE-2023-27997

CRITICALCISA KEVEPSS 100th pctl

9.8

CVSS v3

NVD

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.

CWE-122Heap-based Buffer Overflow CWE-787Out-of-bounds Write

How to fix

Actively exploited, no published fix found yet

CISA required action: Apply updates per vendor instructions.

Federal remediation due: 2023-07-04

Known ransomware campaign use

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

85.69%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

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

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.

Apply updates per vendor instructions.

Remediation due: 2023-07-04

Associated with ransomware campaigns

References

Vendor Advisory1

fortiguard.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2024-26256	High	7.8	88%	-	Fix
CVE-2020-25687	Medium	5.9	87%	-	Fix
CVE-2009-3459	High	8.8	87%	KEV	Fix
CVE-2021-21017	High	8.8	86%	KEV	-
CVE-2020-25683	Medium	5.9	86%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-24.