Stack-based buffer overflow in Fortinet FortiWeb
Priority HIGH 74CWE-121Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- 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
Multiple stack-based buffer overflow vulnerabilities [CWE-121] in the proxy daemon of FortiWeb 5.x all versions, 6.0.7 and below, 6.1.2 and below, 6.2.6 and below, 6.3.16 and below, 6.4 all versions may allow an unauthenticated remote attacker to achieve arbitrary code execution via specifically crafted HTTP requests.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.35221 98th 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
- Yes
- 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 | FortiWeb | 6.4.0 – 6.4.1; 6.3.0 – 6.3.16; 6.2.0 – 6.2.6; 6.1.0 – 6.1.2; 6.0.0 – 6.0.7; 5.9.0 – 5.9.1; 5.8.5 – 5.8.7; 5.8.0 – 5.8.3; 5.7.0 – 5.7.3; 5.6.0 – 5.6.2; 5.8.0 and later; 5.7.0 and later; 5.6.0 and later | — | No fix listed | CNA |
- FortiWeb VendorFortinet Affected 6.4.0 – 6.4.1; 6.3.0 – 6.3.16; 6.2.0 – 6.2.6; 6.1.0 – 6.1.2; 6.0.0 – 6.0.7; 5.9.0 – 5.9.1; 5.8.5 – 5.8.7; 5.8.0 – 5.8.3; 5.7.0 – 5.7.3; 5.6.0 – 5.6.2; 5.8.0 and later; 5.7.0 and later; 5.6.0 and later Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:* | 5.6.0 to before 6.0.8; 6.1.0 to before 6.1.3; 6.2.0 to before 6.2.7; 6.3.0 to before 6.3.17; 6.4.0 – 6.4.2 | Vulnerable | Fortinet |
- cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:* Versions 5.6.0 to before 6.0.8; 6.1.0 to before 6.1.3; 6.2.0 to before 6.2.7; 6.3.0 to before 6.3.17; 6.4.0 – 6.4.2 Vulnerable ·Fortinet
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-42756
- 2026-10-03 Alias added: GHSA-wqmg-f43p-5ccf
References
More Fortinet Fortiweb vulnerabilities
- TI-2026-20057 Authentication bypass in Fortinet FortiWeb KEVCVSS 3.1CRITICAL 9.4
- TI-2025-39856 Path traversal in Fortinet FortiWeb KEVCVSS 3.1CRITICAL 9.4
- TI-2025-18919 SQL injection in Fortinet FortiWeb KEVCVSS 3.1CRITICAL 9.8
- TI-2025-35886 OS command injection in Fortinet FortiWeb KEVCVSS 3.1MEDIUM 6.7
- TI-2021-05113 OS command injection in Fortinet FortiWeb CVSS 3.1HIGH 8.8
- TI-2025-37179 Improper signature verification in Fortinet FortiWeb CVSS 3.1CRITICAL 9.1
Sources
- CVE-2021-42756 · CVE Program
- CVE-2021-42756 · NVD
- FIRST EPSS
- GHSA-wqmg-f43p-5ccf · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences