Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability
Fortinet · FortiOS and FortiProxy SSL-VPN
9.2CriticalCVSS 3.1
Recommended action
Patch now
CISA confirms exploitation in the wild and lists 2023-07-04 as the remediation due date.
Patch available
Direct vendor intelligence
Authoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
1 current
SSA-770770 · CSAF 2.0 · revision 9 · finalSiemens ProductCERTSSA-770770: Multiple Vulnerabilities in Fortigate NGFW Before V7.4.7 on RUGGEDCOM APE1808 Devices
1 known affected
The vendor explicitly identifies these products as affected by this CVE.
RUGGEDCOM APE1808
Summary
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.
Remediation
Update Fortigate NGFW to V7.4.7. Contact customer support to receive patch and update information
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2023-31722
EU known exploited
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.
EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 13 Jun 2023. Evidence sources: cisa_kev, eukev_kev.
ENISA score
9.2 · CVSS 3.1
Advisory evidence
5 linked advisory records
Recommended actionPatch now
CISA confirms exploitation in the wild and lists 2023-07-04 as the remediation due date.
Patch available
01
What, why and how
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.
What
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.
Why
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
What
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.
Why
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.Confirmed in the wild
CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2023-06-13. Known ransomware campaign use is recorded.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.None recorded
No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
Likely attack path
a network path → Heap-based Buffer Overflow → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-122: Heap-based Buffer Overflow. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2023-31722Known-exploited evidence recorded
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.
Official EUVD record ↗BSI · German · WID-SEC-2023-1411Fortinet FortiOS und FortiProxy: Schwachstelle ermöglicht Codeausführung
Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Fortinet FortiOS und FortiProxy ausnutzen, um beliebigen Programmcode auszuführen.
Official advisory ↗Canadian Centre for Cyber Security · English · AL25-005Compromise and persistent access of Fortinet FortiOS products (CVE-2022-42475, CVE-2023-27997, CVE-2024-21762)
An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.
Official advisory ↗Canadian Centre for Cyber Security · English · AL23-006Vulnerability impacting FortiGate/FortiOS (CVE-2023-27997) – Update 2
An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.
Official advisory ↗Canadian Centre for Cyber Security · English · AV23-330Fortinet security advisory (AV23-330)
On June 12, 2023, Fortinet published Security Advisories to address vulnerabilities in multiple products. Included were updates for the following::
Exploitation of some of these vulnerabilities could lead to remote code execution.
Official advisory ↗Cyber Security Agency of Singapore · English · CSA-SB-20230614Security Bulletin 14 Jun 2023
The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 14 Jun 2023, published on 14 June 2023. Open the linked bulletin for the product, severity and reference information published in that issue.
Official advisory ↗CERT-FR · French · CERTFR-2024-AVI-0203Multiples vulnérabilités dans les produits Siemens
Official advisory ↗JVN iPedia · Japanese · JVNDB-2023-002225FortiOS および FortiProxy における境界外書き込みに関する脆弱性
FortiOS および FortiProxy には、境界外書き込みに関する脆弱性が存在します。
Official advisory ↗KISA KrCERT/CC · Korean · KNVD-6448Fortinet 제품 보안 업데이트 권고
FortiOS 및 FortiProxy의 SSL-VPN에서 발생하는 힙 오버플로 취약점(CVE-2023-27997) [1][3][6]
Official advisory ↗KISA KrCERT/CC · Korean · KNVD-5935현재 악용되고 있는 Exploit(Update. 2023-06-13)
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.
Official advisory ↗KISA KrCERT/CC · Korean · KNVD-5933Fortinet 제품 취약점 보안 업데이트 권고
FortiOS SSL-VPN에서 발생하는 원격코드 실행 취약점 (CVE-2023-27997)
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Update Fortigate NGFW to V7.4.7. Contact customer support to receive patch and update information
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 13 Jun 2023 · Last source change 31 Jul 2026, 03:55 UTC · CWE-122 · Heap-based Buffer Overflow
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-08-14
Affected versionsThe structured affected or fixed version information changed.
Before
7.0.10; 7.0.5; 6.4.12; 6.4.10; 6.4.8; 6.4.6; 6.4.2; 6.2.9 ≤ 6.2.13 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
After
FortiOS-6K7K: 7.0.10, 7.0.5, 6.4.12, 6.4.10, 6.4.8, 6.4.6, 6.4.2, 6.2.9 ≤ 6.2.13, 6.2.6 ≤ 6.2.7, 6.2.4, 6.0.12 ≤ 6.0.16, 6.0.10; FortiProxy: 7.2.0 ≤ 7.2.3, 7.0.0 ≤ 7.0.9, 2.0.0 ≤ 2.0.12, 1.2.0 ≤ 1.2.13, 1.1.0 ≤ 1.1.6; FortiOS: 7.2.0 ≤ 7.2.4, 7.0.0 ≤ 7.0.11, 6.4.0 ≤ 6.4.12, 6.2.0 ≤ 6.2.13, 6.0.0 ≤ 6.0.16 · Fixed: Please upgrade to FortiOS-6K7K version 7.0.12 or above; Please upgrade to FortiOS-6K7K version 6.4.13 or above; Please upgrade to FortiOS-6K7K version 6.2.15 or above; Please upgrade to FortiOS-6K7K version 6.0.17 or above; Please upgrade to FortiProxy version 7.2.4 or above; Please upgrade to FortiProxy version 7.0.10 or above; Please upgrade to FortiOS version 7.4.0 or above; Please upgrade to FortiOS version 7.2.5 or above; Please upgrade to FortiOS version 7.0.12 or above; Please upgrade to FortiOS version 6.4.13 or above; Please upgrade to FortiOS version 6.2.14 or above; Please upgrade to FortiOS version 6.0.17 or above
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
