Out-of-bounds write in Fortinet FortiOS
Priority MEDIUM 43CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- 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-787 and the CVSS impact.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01548 75th 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
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Fortinet | Fortinet FortiOS | FortiOS 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, 6.0.0 through 6.0.13 | — | No fix listed | CNA |
- Fortinet FortiOS VendorFortinet Affected FortiOS 7.0.1, 7.0.0, 6.4.0 through 6.4.6, 6.2.0 through 6.2.9, 6.0.0 through 6.0.13 Fixed in — No fix listed CNA
CPE configurations NVD · 16
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:* | 6.0.0 – 6.0.13; 6.2.0 – 6.2.9; 6.4.0 – 6.4.6 | Vulnerable | Fortinet |
| cpe:2.3:o:fortinet:fortios:7.0.0:*:*:*:*:*:*:* | 7.0.0 | Vulnerable | Fortinet |
| cpe:2.3:o:fortinet:fortios:7.0.1:*:*:*:*:*:*:* | 7.0.1 | Vulnerable | Fortinet |
| cpe:2.3:h:fortinet:fortigate-1100e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate-200f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate-2600f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate-3500f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate-400e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate-600e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_1800f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
- cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:* Versions 6.0.0 – 6.0.13; 6.2.0 – 6.2.9; 6.4.0 – 6.4.6 Vulnerable ·Fortinet
- cpe:2.3:o:fortinet:fortios:7.0.0:*:*:*:*:*:*:* Versions 7.0.0 Vulnerable ·Fortinet
- cpe:2.3:o:fortinet:fortios:7.0.1:*:*:*:*:*:*:* Versions 7.0.1 Vulnerable ·Fortinet
- cpe:2.3:h:fortinet:fortigate-1100e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate-200f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate-2600f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate-3500f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate-400e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate-600e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_1800f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
Show 6 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:h:fortinet:fortigate_2200e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_3300e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_3600e:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_40f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_60f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
| cpe:2.3:h:fortinet:fortigate_7121f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Fortinet |
- cpe:2.3:h:fortinet:fortigate_2200e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_3300e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_3600e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_40f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_60f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
- cpe:2.3:h:fortinet:fortigate_7121f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Fortinet
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-36173
- 2026-10-03 Alias added: GHSA-p5m6-c47j-fg8m
References
More Fortinet Fortios vulnerabilities
- 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
Sources
- CVE-2021-36173 · CVE Program
- CVE-2021-36173 · NVD
- FIRST EPSS
- GHSA-p5m6-c47j-fg8m · GitHub Advisory Database · CC BY 4.0
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