CVE-2023-20031Network attack vector

Inspection bypass via concurrent TLS certificate access

Published Nov 1, 2023 · Updated Aug 2, 2024

A logic error in Cisco Firepower Threat Defense Software allows remote attackers to restart Snort 3 by flooding inspected TLS connections. The integration accesses an SSL/TLS certificate while it is initiating a connection and under load, so timing-constrained concurrent requests trigger an automatic engine reload. Exposure requires Snort 3 and either TLS server identity discovery or an SSL policy; the reload creates an inspection bypass or temporary service interruption.

CVSS severity4.0
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A logic error in Cisco Firepower Threat Defense Software allows remote attackers to restart Snort 3 by flooding inspected TLS connections. The integration accesses an SSL/TLS certificate while it is initiating a connection and under load, so timing-constrained concurrent requests trigger an automatic engine reload. Exposure requires Snort 3 and either TLS server identity discovery or an SSL policy; the reload creates an inspection bypass or temporary service interruption.

The record

CVE
CVE-2023-20031
Published
Nov 1, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco Firepower Threat Defense Software
Classifications
CWE-244, T1499.004, T1562.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 1, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=6.7.0
  2. Affected versionversion=6.7.0.1
  3. Affected versionversion=6.7.0.2
  4. Affected versionversion=6.7.0.3
  5. Affected versionversion=7.0.0
  6. Affected versionversion=7.0.0.1
  7. Affected versionversion=7.0.1
  8. Affected versionversion=7.0.1.1
  9. Affected versionversion=7.0.2
  10. Affected versionversion=7.0.2.1
  11. Affected versionversion=7.0.3
  12. Affected versionversion=7.0.4
  13. Affected versionversion=7.0.5
  14. Affected versionversion=7.2.0
  15. Affected versionversion=7.2.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Firepower Threat Defense Softwareversion=6.7.0; version=6.7.0.1; version=6.7.0.2; version=6.7.0.3; version=7.0.0; version=7.0.0.1; version=7.0.1; version=7.0.1.1; version=7.0.2; version=7.0.2.1; version=7.0.3; version=7.0.4; version=7.0.5; version=7.2.0; version=7.2.0.1

Published CVSS scores

4.0Cisco Systems, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
5.4NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-244Improper Clearing of Heap Memory Before Release ('Heap Inspection')
T1499.004Application or System Exploitation
T1562.001Disable or Modify Tools

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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