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 4y ago modified 2026-06-17 4mo 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.

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Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 Intel 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.