CVE-2023-20213

CDP process crash via insufficient bounds checking

Published Nov 1, 2023 · Updated Jun 12, 2025

Denial of service in affected Cisco Identity Services Engine releases allows attackers to crash the CDP process with crafted traffic. The CDP processing feature performs insufficient bounds checking while parsing crafted CDP traffic, causing an out-of-bounds write and process termination. The sender requires Layer 2 adjacency but no authentication; a crash disrupts neighbor discovery and remote-device reachability until the process is manually restarted.

CVSS severity4.3
Medium
EPSS probability0.30%
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 affected Cisco Identity Services Engine releases allows attackers to crash the CDP process with crafted traffic. The CDP processing feature performs insufficient bounds checking while parsing crafted CDP traffic, causing an out-of-bounds write and process termination. The sender requires Layer 2 adjacency but no authentication; a crash disrupts neighbor discovery and remote-device reachability until the process is manually restarted.

The record

CVE
CVE-2023-20213
Published
Nov 1, 2023
Updated
Jun 12, 2025
Vendor
ClamAV
Product
Cisco Identity Services Engine
Classifications
CWE-787, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Jun 12, 2025Record 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=2.6.0
  2. Affected versionversion=2.6.0 p1
  3. Affected versionversion=2.6.0 p10
  4. Affected versionversion=2.6.0 p11
  5. Affected versionversion=2.6.0 p12
  6. Affected versionversion=2.6.0 p2
  7. Affected versionversion=2.6.0 p3
  8. Affected versionversion=2.6.0 p5
  9. Affected versionversion=2.6.0 p6
  10. Affected versionversion=2.6.0 p7
  11. Affected versionversion=2.6.0 p8
  12. Affected versionversion=2.6.0 p9
  13. Affected versionversion=2.7.0
  14. Affected versionversion=2.7.0 p1
  15. Affected versionversion=2.7.0 p2
  16. Affected versionversion=2.7.0 p3
  17. Affected versionversion=2.7.0 p4
  18. Affected versionversion=2.7.0 p5
  19. Affected versionversion=2.7.0 p6
  20. Affected versionversion=2.7.0 p7
  21. Affected versionversion=2.7.0 p9
  22. Affected versionversion=3.0.0
  23. Affected versionversion=3.0.0 p1
  24. Affected versionversion=3.0.0 p2
  25. Affected versionversion=3.0.0 p3
  26. Affected versionversion=3.0.0 p4
  27. Affected versionversion=3.0.0 p5
  28. Affected versionversion=3.0.0 p6
  29. Affected versionversion=3.1.0
  30. Affected versionversion=3.1.0 p1
  31. Affected versionversion=3.1.0 p3
  32. Affected versionversion=3.1.0 p4
  33. Affected versionversion=3.1.0 p5
  34. Affected versionversion=3.1.0 p7
  35. Affected versionversion=3.2.0
  36. Affected versionversion=3.2.0 p1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Identity Services Engineversion=2.6.0; version=2.6.0 p1; version=2.6.0 p10; version=2.6.0 p11; version=2.6.0 p12; version=2.6.0 p2; version=2.6.0 p3; version=2.6.0 p5; version=2.6.0 p6; version=2.6.0 p7; version=2.6.0 p8; version=2.6.0 p9; version=2.7.0; version=2.7.0 p1; version=2.7.0 p2; version=2.7.0 p3; version=2.7.0 p4; version=2.7.0 p5; version=2.7.0 p6; version=2.7.0 p7; version=2.7.0 p9; version=3.0.0; version=3.0.0 p1; version=3.0.0 p2; version=3.0.0 p3; version=3.0.0 p4; version=3.0.0 p5; version=3.0.0 p6; version=3.1.0; version=3.1.0 p1; version=3.1.0 p3; version=3.1.0 p4; version=3.1.0 p5; version=3.1.0 p7; version=3.2.0; version=3.2.0 p1

Published CVSS scores

4.3Cisco Systems, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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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