CVE-2021-36173
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions...
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, and 6.0.0 through 6.0.13 may allow an attacker to execute arbitrary code via specially crafted installation images.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, and 6.0.0 through 6.0.13 may allow an attacker to execute arbitrary code via specially crafted installation images.
- Record
CVE-2021-36173- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:W/RC:C - Updated
- 2026-11-02
EUVDEUVD-2021-22794
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, and 6.0.0 through 6.0.13 may allow an attacker to execute arbitrary code via specially crafted installation images.
- Record
EUVD-2021-22794- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:W/RC:C - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-p5m6-c47j-fg8m No score
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions...
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, and 6.0.0 through 6.0.13 may allow an attacker to execute arbitrary code via specially crafted installation images.
- Record
GHSA-p5m6-c47j-fg8m- Weakness
- CWE-787
- Updated
- 2026-11-02
NVD
A heap-based buffer overflow in the firmware signature verification function of FortiOS versions 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, and 6.0.0 through 6.0.13 may allow an attacker to execute arbitrary code via specially crafted installation images.
- Record
CVE-2021-36173- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - CVSS 2.0
- 6.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-787
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-36173 is a high vulnerability (CVSS 8.0) in Fortinet Fortios, published December 8, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.55%, the 75th percentile. No source names a fixed version.