CVE-2020-3308Network attack vector

Attacker-controlled patch boot via unsigned image acceptance

Published May 6, 2020 · Updated Nov 15, 2024

Signature verification bypass in Cisco Firepower Threat Defense before 6.2.2.1 allows remote authenticated users to boot unsigned patch images. The Image Signature Verification feature improperly accepts a crafted patch without a valid digital signature and permits it to become the booted software image. Administrator-level credentials and patch-upload access are required; exploitation replaces trusted firewall software with attacker-controlled code.

CVSS severity4.9
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature verification bypass in Cisco Firepower Threat Defense before 6.2.2.1 allows remote authenticated users to boot unsigned patch images. The Image Signature Verification feature improperly accepts a crafted patch without a valid digital signature and permits it to become the booted software image. Administrator-level credentials and patch-upload access are required; exploitation replaces trusted firewall software with attacker-controlled code.

The record

CVE
CVE-2020-3308
Published
May 6, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco Firepower Threat Defense
Classifications
CWE-347
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 6, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

ClamAV · Cisco Firepower Threat Defenseversion=n/a

Published CVSS scores

4.9NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
4.9Cisco Systems, Inc.CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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