A buffer overflow [CWE-121] in the TFTP client library of FortiOS before 6.4.7 and FortiOS 7.0.0 through 7.0.2, may allow an authenticated…

published 2021-12-08 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29715

cvss: 6.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits: 0; none known

A buffer overflow [CWE-121] in the TFTP client library of FortiOS before 6.4.7 and FortiOS 7.0.0 through 7.0.2, may allow an authenticated local attacker to achieve arbitrary code execution via specially crafted command line arguments.

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.3	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:C
CNA	3.1	6.7	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	6.7	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	4.6	AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

Fortinet FortiOS
Fortinet FortiDDoS-F
Fortinet FortiVoice
Fortinet FortiProxy
Fortinet FortiRecorder
Fortinet FortiPortal
Fortinet FortiMail
Fortinet FortiAnalyzer
Fortinet FortiNDR
Fortinet FortiDDoS
Fortinet FortiSwitch
Fortinet FortiADC
Fortinet FortiWeb
Fortinet FortiManager

Classification

Weakness

CWE-120 Buffer Copy without Checking Size of Input
CWE-787 Out-of-bounds Write

Technology feeds

Fortinet rss critical rss

References

fortiguard.com /advisory/FG-IR-21-173
vendor-advisory

Sources

CVE List CVE-2021-42757
NVD CVE-2021-42757

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary