CVE-2021-36173

mediumpriority · track · 36EPSS 0.015 · 75 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.55% (75th) EPSS

CVSS 6.8 · medium

Is it mine?

14 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-22

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.

cvss

Technical severity, 0–10. One row per scoring source.

8.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–8.8

v2.06.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 6.4

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.9

v3.18.8highAV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.18highCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:W/RC:Csecondary · ENISA EU

v3.18highCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · psirt@fortinet.comexploitability 2.1 · impact 5.9

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-787USprimaryCWE-122USCWE-787US

affected products (14)

Products and version ranges known to be affected.

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 6.0.13enisa_euvdEU
Fortinet Inc. FortiOS≤ 7.0.0fstec_bduRU
Fortinet Inc. FortiOS≤ 7.0.1fstec_bduRU
Fortinet Inc. FortiOS6.0.0 → 6.0.13fstec_bduRU
Fortinet Inc. FortiOS6.2.0 → 6.2.9fstec_bduRU
Fortinet Inc. FortiOS6.4.0 → 6.4.6fstec_bduRU
Fortinet Inc. FortiOS-6K7K≤ 6.2.8fstec_bduRU
Fortinet Inc. FortiOS-6K7K≤ 6.0.10fstec_bduRU
Fortinet Inc. FortiOS-6K7K≤ 6.4.5fstec_bduRU
fortinet fortios6.0.0 → 6.0.13nvdUScpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
fortinet fortios6.2.0 → 6.2.9nvdUScpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
fortinet fortios6.4.0 → 6.4.6nvdUScpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
fortinet fortios= 7.0.0nvdUScpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
fortinet fortios= 7.0.1nvdUScpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2021-12-08modified 2026-06-17

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+16021 more

references (6)

External citations — patches, advisories, analysis.

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