CVE-2023-27997
Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability
Fortinet FortiOS and FortiProxy SSL-VPN
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.
Ransomware groups exploiting CVE-2023-27997
The group emerged in mid-February 2024 and has already listed several organizations as alleged victims of their attacks, resulting from extortion through encryption and data leaks. The announcement of the sale of the new Ransomware-as-a-Service (RaaS) by Ranso
Exploitation is attributed to these groups across their recorded activity. It does not follow that every organisation they listed was reached through CVE-2023-27997 — the source data does not record an entry point per incident.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 13 June 2023. US federal agencies were required to remediate it by 4 July 2023. CISA records this vulnerability as known to be used in ransomware campaigns.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 85.7%, which is higher than 99.7% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Recent listings by these groups
Disclosures from the groups above, newest first.
Frequently asked questions
Is CVE-2023-27997 being exploited by ransomware groups?
Yes. CVE-2023-27997 is recorded as exploited by Ransomhub. Between them these groups account for 842 victim disclosures in this database. CISA also records this vulnerability as used in ransomware campaigns.
What does CVE-2023-27997 affect?
CVE-2023-27997 affects Fortinet FortiOS and FortiProxy SSL-VPN. 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.
How severe is CVE-2023-27997?
CVE-2023-27997 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 85.7%, higher than 99.7% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 4 July 2023.
How should organisations respond to CVE-2023-27997?
Apply the vendor patch for Fortinet FortiOS and FortiProxy SSL-VPN as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.