CVE-2021-43074

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-02-16 · updated 2026-06-17
Weakness: CWE-347

Description

An improper verification of cryptographic signature vulnerability [CWE-347] in FortiWeb 6.4 all versions, 6.3.16 and below, 6.2 all versions, 6.1 all versions, 6.0 all versions; FortiOS 7.0.3 and below, 6.4.8 and below, 6.2 all versions, 6.0 all versions; FortiSwitch 7.0.3 and below, 6.4.10 and below, 6.2 all versions, 6.0 all versions; FortiProxy 7.0.1 and below, 2.0.7 and below, 1.2 all versions, 1.1 all versions, 1.0 all versions may allow an attacker to decrypt portions of the administrative session management cookie if able to intercept the latter.

Affected products

Fortinet FortiOS (FortiGate): from 6.0.0 before 6.4.9; from 7.0.0 before 7.0.4 — fixed in 6.4.9, 7.0.4
Fortinet FortiProxy: from 1.0.0 before 2.0.8; from 7.0.0 before 7.0.2 — fixed in 2.0.8, 7.0.2
Fortinet FortiSwitch: from 6.0.0 before 6.4.11; from 7.0.0 before 7.0.4 — fixed in 6.4.11, 7.0.4
Fortinet FortiWeb: from 6.0.0 before 6.3.17; from 6.4.0 before 7.0.0 — fixed in 6.3.17, 7.0.0

How to fix

Upgrade to a fixed version: Fortinet FortiOS (FortiGate) 6.4.9, 7.0.4; Fortinet FortiProxy 2.0.8, 7.0.2; Fortinet FortiSwitch 6.4.11, 7.0.4; Fortinet FortiWeb 6.3.17, 7.0.0. Check the vendor advisory for mitigations.

References

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