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TI-2020-10189 Aliases CVE-2020-12820GHSA-8hp7-6mr2-85pv

Stack-based buffer overflow in Fortinet FortiOS

Priority MEDIUM 40CWE-121Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-121 and the CVSS impact.

Summary

Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00887 59th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
FortinetFortiOS6.0.0 – 6.0.10; 5.6.0 – 5.6.12—No fix listedCNA
  • FortiOS VendorFortinet Affected 6.0.0 – 6.0.10; 5.6.0 – 5.6.12 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*before 5.6.13; 6.0.0 to before 6.0.11VulnerableFortinet
  • cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:* Versions before 5.6.13; 6.0.0 to before 6.0.11 Vulnerable ·Fortinet

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-12820
  2. 2026-10-03 Alias added: GHSA-8hp7-6mr2-85pv

References

Advisory 1

  • TI-2026-20057 Authentication bypass in Fortinet FortiWeb KEVCVSS 3.1CRITICAL 9.4
  • TI-2025-18911 Heap-based buffer overflow in Fortinet FortiSwitchManager KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-36904 Authentication bypass in Fortinet FortiOS KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-15234 A use of externally-controlled format string in Fortinet FortiOS versions 7.4.0 through… KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-14448 Out-of-bounds write in Fortinet FortiOS KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-12585 Heap-based buffer overflow in Fortinet FortiOS-6K7K KEVCVSS 3.1CRITICAL 9.8
See all 276 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences