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CVE-2021-24020

CRITICAL
9.8
CVSS Score
Published: July 9, 2021 at 06:17 PM UTC
Updated: June 17, 2026 at 03:39 AM UTC
1 product affected across 1 vendorFortiMail

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Severity
CRITICAL9.8
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

A missing cryptographic step in the implementation of the hash digest algorithm in FortiMail 6.4.0 through 6.4.4, and 6.2.0 through 6.2.7 may allow an unauthenticated attacker to tamper with signed URLs by appending further data which allows bypass of signature verification.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

FortiMail· Fortinet
95%
v ≤ 6.4.46.2.0 ≤ v ≤ 6.2.76.4.0 ≤ v < 6.4.5
Affected range stops below 6.4.5, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://fortiguard.com/advisory/FG-IR-21-027

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

9.8CRITICAL[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-347

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