CVE-2023-20083Network attack vector

Traffic-processing denial of service via ICMPv6 parsing

Published Nov 1, 2023 · Updated Aug 2, 2024

Denial of service in Cisco Firepower Threat Defense allows remote attackers to stop traffic processing with crafted ICMPv6 packets. The Snort 2 ICMPv6 parser improperly checks header fields, allowing a crafted packet to drive the detection engine into CPU exhaustion. Exposure requires Snort 2 and a nondefault network discovery policy with host and application detection; traffic forwarding stops, while management traffic remains available.

CVSS severity8.6
High
EPSS probability0.69%
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 Firepower Threat Defense allows remote attackers to stop traffic processing with crafted ICMPv6 packets. The Snort 2 ICMPv6 parser improperly checks header fields, allowing a crafted packet to drive the detection engine into CPU exhaustion. Exposure requires Snort 2 and a nondefault network discovery policy with host and application detection; traffic forwarding stops, while management traffic remains available.

The record

CVE
CVE-2023-20083
Published
Nov 1, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco Firepower Threat Defense
Classifications
CWE-835, T1499.004
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=6.2.3
  2. Affected versionversion=6.2.3.1
  3. Affected versionversion=6.2.3.10
  4. Affected versionversion=6.2.3.11
  5. Affected versionversion=6.2.3.12
  6. Affected versionversion=6.2.3.13
  7. Affected versionversion=6.2.3.14
  8. Affected versionversion=6.2.3.15
  9. Affected versionversion=6.2.3.16
  10. Affected versionversion=6.2.3.17
  11. Affected versionversion=6.2.3.18
  12. Affected versionversion=6.2.3.2
  13. Affected versionversion=6.2.3.3
  14. Affected versionversion=6.2.3.4
  15. Affected versionversion=6.2.3.5
  16. Affected versionversion=6.2.3.6
  17. Affected versionversion=6.2.3.7
  18. Affected versionversion=6.2.3.8
  19. Affected versionversion=6.2.3.9
  20. Affected versionversion=6.4.0
  21. Affected versionversion=6.4.0.1
  22. Affected versionversion=6.4.0.10
  23. Affected versionversion=6.4.0.11
  24. Affected versionversion=6.4.0.12
  25. Affected versionversion=6.4.0.13
  26. Affected versionversion=6.4.0.14
  27. Affected versionversion=6.4.0.15
  28. Affected versionversion=6.4.0.16
  29. Affected versionversion=6.4.0.17
  30. Affected versionversion=6.4.0.2
  31. Affected versionversion=6.4.0.3
  32. Affected versionversion=6.4.0.4
  33. Affected versionversion=6.4.0.5
  34. Affected versionversion=6.4.0.6
  35. Affected versionversion=6.4.0.7
  36. Affected versionversion=6.4.0.8
  37. Affected versionversion=6.4.0.9
  38. Affected versionversion=6.6.0
  39. Affected versionversion=6.6.0.1
  40. Affected versionversion=6.6.1
  41. Affected versionversion=6.6.3
  42. Affected versionversion=6.6.4
  43. Affected versionversion=6.6.5
  44. Affected versionversion=6.6.5.1
  45. Affected versionversion=6.6.5.2
  46. Affected versionversion=6.6.7
  47. Affected versionversion=6.6.7.1
  48. Affected versionversion=6.7.0
  49. Affected versionversion=6.7.0.1
  50. Affected versionversion=6.7.0.2
  51. Affected versionversion=6.7.0.3
  52. Affected versionversion=7.0.0
  53. Affected versionversion=7.0.0.1
  54. Affected versionversion=7.0.1
  55. Affected versionversion=7.0.1.1
  56. Affected versionversion=7.0.2
  57. Affected versionversion=7.0.2.1
  58. Affected versionversion=7.0.3
  59. Affected versionversion=7.0.4
  60. Affected versionversion=7.0.5
  61. Affected versionversion=7.1.0
  62. Affected versionversion=7.1.0.1
  63. Affected versionversion=7.1.0.2
  64. Affected versionversion=7.1.0.3
  65. Affected versionversion=7.2.0
  66. Affected versionversion=7.2.0.1
  67. Affected versionversion=7.2.1
  68. Affected versionversion=7.2.2
  69. Affected versionversion=7.2.3
  70. Affected versionversion=7.3.0
  71. Affected versionversion=7.3.1
  72. Affected versionversion=7.3.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Firepower Threat Defenseversion=6.2.3; version=6.2.3.1; version=6.2.3.10; version=6.2.3.11; version=6.2.3.12; version=6.2.3.13; version=6.2.3.14; version=6.2.3.15; version=6.2.3.16; version=6.2.3.17; version=6.2.3.18; version=6.2.3.2; version=6.2.3.3; version=6.2.3.4; version=6.2.3.5; version=6.2.3.6; version=6.2.3.7; version=6.2.3.8; version=6.2.3.9; version=6.4.0; version=6.4.0.1; version=6.4.0.10; version=6.4.0.11; version=6.4.0.12; version=6.4.0.13; version=6.4.0.14; version=6.4.0.15; version=6.4.0.16; version=6.4.0.17; version=6.4.0.2; version=6.4.0.3; version=6.4.0.4; version=6.4.0.5; version=6.4.0.6; version=6.4.0.7; version=6.4.0.8; version=6.4.0.9; version=6.6.0; version=6.6.0.1; version=6.6.1; version=6.6.3; version=6.6.4; version=6.6.5; version=6.6.5.1; version=6.6.5.2; version=6.6.7; version=6.6.7.1; version=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=7.1.0; version=7.1.0.1; version=7.1.0.2; version=7.1.0.3; version=7.2.0; version=7.2.0.1; version=7.2.1; version=7.2.2; version=7.2.3; version=7.3.0; version=7.3.1; version=7.3.1.1

Published CVSS scores

8.6Cisco Systems, Inc.CVSS: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 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-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

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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