CVE-2021-42756: fortinet fortiweb Stack-based Buffer Overflow
Vulnerability summary
CVE-2021-42756 is a critical (CVSS 9.8) Stack-based Buffer Overflow vulnerability in fortinet fortiweb. EPSS estimates a 34.98% chance of exploitation in the next 30 days, higher than 98.4% of scored vulnerabilities.
Timeline
- 16-02-2023PublishedVulnerability first disclosed.
- 23-10-2024Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
2 scores · 2 sources · 1 version- CVE.orgCNA9.3CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:CDiffers
EPSS trend
Probability
34.98%
Chance of exploitation in the next 30 days
Percentile
98%
Versus all other CVEs
30-day change
0.00 pp
From 34.98% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Fortinet1 product
- 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, < 5.8.* | ≥ 5.7.0, < 5.7.* | ≥ 5.6.0, < 5.6.* | ≥ 5.6.0, < 6.0.8 | ≥ 6.1.0, < 6.1.3 | ≥ 6.2.0, < 6.2.7 | ≥ 6.3.0, < 6.3.17 | ≥ 6.4.0, ≤ 6.4.2
1 vendor · 1 product
References
1 links- fortiguard.com/psirt/FG-IR-21-186Vendor Advisory