Cyber Resilience

CVE-2023-27997

Memory Safety in Fortinet Fortios 6.0.0 – 6.0.16

CISA KEVActive ExploitationEUVD ExploitedRansomware-linkedMemory Safety
Published
13 June 2023
Modified
31 July 2026
KEV Added
13 June 2023
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.86 99.7th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2023-27997 is a critical-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Fortinet Fortios. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 0.3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A heap-based buffer overflow vulnerability, tracked as CWE-122 and CWE-787, affects the SSL-VPN component of FortiOS versions 7.2.4 and below, 7.0.11 and below, 6.4.12 and below, and 6.0.16 and below, as well as FortiProxy versions 7.2.3 and below, 7.0.9 and below, 2.0.12 and below, and all versions of 1.2 and 1.1. The flaw permits remote attackers to supply specially crafted requests that trigger memory corruption, leading to arbitrary code or command execution. It carries a CVSS 3.1 base score of 9.8, reflecting network-accessible, unauthenticated attack vectors with high impact on confidentiality, integrity, and availability.

An unauthenticated remote attacker can target exposed SSL-VPN interfaces to achieve full code execution on affected Fortinet appliances without user interaction. Successful exploitation grants the attacker the ability to run arbitrary commands, potentially resulting in complete device compromise, lateral movement, or persistence within the target network.

Fortinet’s PSIRT advisory FG-IR-23-097 details the affected releases and remediation steps, while CISA’s Known Exploited Vulnerabilities catalog confirms active exploitation in the wild. The associated EPSS score has remained consistently high, with a current value of 0.9141 and a recorded peak of 0.9242, underscoring sustained attacker interest following disclosure.

EU & UK References

Vulnerability Data

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…

more

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(s)
CWE-122CWE-787
KEV Date Added
13 June 2023

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2018-13383Same product: Fortinet Fortiosboth on KEV
CVE-2024-21762Same product: Fortinet Fortiosboth on KEV
CVE-2023-22639Same product: Fortinet Fortios
CVE-2023-42789Same product: Fortinet Fortios
CVE-2023-22640Same product: Fortinet Fortios
CVE-2022-42475Same product: Fortinet Fortiosboth on KEV
CVE-2023-33308Same product: Fortinet Fortios
CVE-2025-25249Same product: Fortinet Fortios
CVE-2025-57740Same product: Fortinet Fortios
CVE-2023-29182Same product: Fortinet Fortios

Affected Assets

fortinet
fortiproxy
1.1.0 — 1.1.6 · 1.2.0 — 1.2.13 · 2.0.0 — 2.0.12
fortinet
fortios
6.0.10, 6.2.4, 6.2.6, 6.2.7, 6.4.10 · 6.0.0 — 6.0.16 · 6.2.0 — 6.2.13 · 6.4.0 — 6.4.12

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.4.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.

PR.PS-02 partial match
prevents

Timely patching removes known heap-overflow instances after they exist.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can detect heap overflows before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.

A.8.32 Change management partial match
prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References