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CVE-2023-27997: Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability

CVE-2023-27997 is rated critical with a CVSS v3.1 base score of 9.8 and affects Fortinet FortiOS and FortiProxy SSL-VPN. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-06-13, which means exploitation in the wild has been observed.

Vulnerability 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.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-122: Heap-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the heap.

CWE-787: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

Affected products

  • Fortinet Fortiproxy: from 1.1.0 up to and including 1.1.6; from 1.2.0 up to and including 1.2.13; from 2.0.0 up to and including 2.0.12; from 7.0.0 up to and including 7.0.9; from 7.2.0 up to and including 7.2.3
  • Fortinet Fortios: from 6.0.0 up to and including 6.0.16; from 6.2.0 up to and including 6.2.13; from 6.4.0 up to and including 6.4.12; from 7.0.0 up to and including 7.0.11; from 7.2.0 up to and including 7.2.4; from 6.0.12 up to and including 6.0.16; from 6.2.9 up to and including 6.2.13; 6.0.10; 6.2.4; 6.2.6; 6.2.7; 6.4.2

References