CVE-2023-20006Network attack vector

Remote device reload via hardware-offloaded SSL/TLS processing

Published Jun 28, 2023 · Updated Aug 2, 2024

Denial of service in Cisco ASA 9.16.4, 9.18.2, and 9.18.2.5 and FTD 7.2.1 through 7.2.3 allows remote attackers to reload devices. Hardware-offloaded cryptographic functions mishandle a crafted stream of SSL/TLS traffic, triggering an unexpected cryptography-engine error and device reload. Exposure requires a Firepower 2100 appliance configured for SSL/TLS; ASA accepts any terminated SSL/TLS connection, while FTD is limited to SSL Decrypt Policies and Remote Access VPN.

CVSS severity8.6
High
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco ASA 9.16.4, 9.18.2, and 9.18.2.5 and FTD 7.2.1 through 7.2.3 allows remote attackers to reload devices. Hardware-offloaded cryptographic functions mishandle a crafted stream of SSL/TLS traffic, triggering an unexpected cryptography-engine error and device reload. Exposure requires a Firepower 2100 appliance configured for SSL/TLS; ASA accepts any terminated SSL/TLS connection, while FTD is limited to SSL Decrypt Policies and Remote Access VPN.

The record

CVE
CVE-2023-20006
Published
Jun 28, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco Adaptive Security Appliance (ASA) Software
Classifications
CWE-681, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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=9.16.4
  2. Affected versionversion=9.18.2
  3. Affected versionversion=9.18.2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Adaptive Security Appliance (ASA) Softwareversion=9.16.4; version=9.18.2; version=9.18.2.5
ClamAV · Cisco Firepower Threat Defenseversion=7.2.1; version=7.2.2; version=7.2.3

Published CVSS scores

8.6Cisco PSIRTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-681Incorrect Conversion between Numeric Types
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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