CVE-2023-20190Network attack vector

ACL bypass via reused destination mask

Published Sep 13, 2023 · Updated Aug 2, 2024

Authorization flaw in classic ACL compression in Cisco IOS XR Software allows remote attackers to bypass configured IPv4 ACL protections. When level 2 or 3 compression finds duplicate destination addresses, it reuses the first ACE's destination mask for later entries instead of preserving each mask. Exposure requires a classic IPv4 ACL with compression enabled and duplicate destinations with different masks; bypassed traffic can reach protected networks.

CVSS severity5.8
Medium
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization flaw in classic ACL compression in Cisco IOS XR Software allows remote attackers to bypass configured IPv4 ACL protections. When level 2 or 3 compression finds duplicate destination addresses, it reuses the first ACE's destination mask for later entries instead of preserving each mask. Exposure requires a classic IPv4 ACL with compression enabled and duplicate destinations with different masks; bypassed traffic can reach protected networks.

The record

CVE
CVE-2023-20190
Published
Sep 13, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-264, CWE-863, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 13, 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=5.2.0
  2. Affected versionversion=5.2.1
  3. Affected versionversion=5.2.2
  4. Affected versionversion=5.2.3
  5. Affected versionversion=5.2.4
  6. Affected versionversion=5.2.47
  7. Affected versionversion=5.2.5
  8. Affected versionversion=5.3.0
  9. Affected versionversion=5.3.1
  10. Affected versionversion=5.3.2
  11. Affected versionversion=5.3.3
  12. Affected versionversion=5.3.4
  13. Affected versionversion=6.0.0
  14. Affected versionversion=6.0.1
  15. Affected versionversion=6.0.2
  16. Affected versionversion=6.1.1
  17. Affected versionversion=6.1.12
  18. Affected versionversion=6.1.2
  19. Affected versionversion=6.1.22
  20. Affected versionversion=6.1.3
  21. Affected versionversion=6.1.32
  22. Affected versionversion=6.1.36
  23. Affected versionversion=6.1.4
  24. Affected versionversion=6.1.42
  25. Affected versionversion=6.2.1
  26. Affected versionversion=6.2.11
  27. Affected versionversion=6.2.2
  28. Affected versionversion=6.2.25
  29. Affected versionversion=6.2.3
  30. Affected versionversion=6.3.15
  31. Affected versionversion=6.3.2
  32. Affected versionversion=6.3.3
  33. Affected versionversion=6.4.1
  34. Affected versionversion=6.4.2
  35. Affected versionversion=6.4.3
  36. Affected versionversion=6.5.1
  37. Affected versionversion=6.5.2
  38. Affected versionversion=6.5.25
  39. Affected versionversion=6.5.26
  40. Affected versionversion=6.5.28
  41. Affected versionversion=6.5.29
  42. Affected versionversion=6.5.3
  43. Affected versionversion=6.5.32
  44. Affected versionversion=6.5.33
  45. Affected versionversion=6.6.2
  46. Affected versionversion=6.6.25
  47. Affected versionversion=6.6.3
  48. Affected versionversion=6.6.4
  49. Affected versionversion=6.7.1
  50. Affected versionversion=6.7.2
  51. Affected versionversion=6.7.3
  52. Affected versionversion=6.7.4
  53. Affected versionversion=6.8.1
  54. Affected versionversion=6.8.2
  55. Affected versionversion=6.9.1
  56. Affected versionversion=6.9.2
  57. Affected versionversion=7.0.1
  58. Affected versionversion=7.0.12
  59. Affected versionversion=7.0.14
  60. Affected versionversion=7.0.2
  61. Affected versionversion=7.1.1
  62. Affected versionversion=7.1.15
  63. Affected versionversion=7.1.2
  64. Affected versionversion=7.1.3
  65. Affected versionversion=7.2.0
  66. Affected versionversion=7.2.1
  67. Affected versionversion=7.2.2
  68. Affected versionversion=7.3.1
  69. Affected versionversion=7.3.15
  70. Affected versionversion=7.3.2
  71. Affected versionversion=7.3.3
  72. Affected versionversion=7.4.1
  73. Affected versionversion=7.4.2
  74. Affected versionversion=7.5.1
  75. Affected versionversion=7.5.2
  76. Affected versionversion=7.5.3
  77. Affected versionversion=7.6.1
  78. Affected versionversion=7.6.2
  79. Affected versionversion=7.7.1
  80. Affected versionversion=7.7.2
  81. Affected versionversion=7.8.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=5.2.0; version=5.2.1; version=5.2.2; version=5.2.3; version=5.2.4; version=5.2.47; version=5.2.5; version=5.3.0; version=5.3.1; version=5.3.2; version=5.3.3; version=5.3.4; version=6.0.0; version=6.0.1; version=6.0.2; version=6.1.1; version=6.1.12; version=6.1.2; version=6.1.22; version=6.1.3; version=6.1.32; version=6.1.36; version=6.1.4; version=6.1.42; version=6.2.1; version=6.2.11; version=6.2.2; version=6.2.25; version=6.2.3; version=6.3.15; version=6.3.2; version=6.3.3; version=6.4.1; version=6.4.2; version=6.4.3; version=6.5.1; version=6.5.2; version=6.5.25; version=6.5.26; version=6.5.28; version=6.5.29; version=6.5.3; version=6.5.32; version=6.5.33; version=6.6.2; version=6.6.25; version=6.6.3; version=6.6.4; version=6.7.1; version=6.7.2; version=6.7.3; version=6.7.4; version=6.8.1; version=6.8.2; version=6.9.1; version=6.9.2; version=7.0.1; version=7.0.12; version=7.0.14; version=7.0.2; version=7.1.1; version=7.1.15; version=7.1.2; version=7.1.3; version=7.2.0; version=7.2.1; version=7.2.2; version=7.3.1; version=7.3.15; version=7.3.2; version=7.3.3; version=7.4.1; version=7.4.2; version=7.5.1; version=7.5.2; version=7.5.3; version=7.6.1; version=7.6.2; version=7.7.1; version=7.7.2; version=7.8.1

Published CVSS scores

5.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.8Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/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-264Permissions, Privileges, and Access Controls
CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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