CVE-2025-20160Network attack vector

Authentication bypass via absent TACACS+ secret validation

Published Sep 24, 2025 · Updated Feb 26, 2026

Authentication bypass in Cisco IOS and IOS XE Software allows man-in-the-middle attackers to read TACACS+ data or access devices. The TACACS+ implementation fails to verify that every configured server has a shared secret, leaving messages unencrypted and accepting replies from an impersonated server. Exploitation requires a machine-in-the-middle position and TACACS+ configuration with at least one server missing its shared secret; disclosure is limited to message contents, while forged acceptance grants device access.

CVSS severity8.1
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Cisco IOS and IOS XE Software allows man-in-the-middle attackers to read TACACS+ data or access devices. The TACACS+ implementation fails to verify that every configured server has a shared secret, leaving messages unencrypted and accepting replies from an impersonated server. Exploitation requires a machine-in-the-middle position and TACACS+ configuration with at least one server missing its shared secret; disclosure is limited to message contents, while forged acceptance grants device access.

The record

CVE
CVE-2025-20160
Published
Sep 24, 2025
Updated
Feb 26, 2026
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-287, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record 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=15.2(4)E10
  2. Affected versionversion=15.2(4)E10a
  3. Affected versionversion=15.2(4)E10d
  4. Affected versionversion=15.2(4)E6
  5. Affected versionversion=15.2(4)E7
  6. Affected versionversion=15.2(4)E8
  7. Affected versionversion=15.2(4)E9
  8. Affected versionversion=15.2(6)E1
  9. Affected versionversion=15.2(6)E2
  10. Affected versionversion=15.2(6)E2a
  11. Affected versionversion=15.2(6)E2b
  12. Affected versionversion=15.2(6)E3
  13. Affected versionversion=15.2(6)EB
  14. Affected versionversion=15.2(7a)E0b
  15. Affected versionversion=15.2(7b)E0b
  16. Affected versionversion=15.2(7)E
  17. Affected versionversion=15.2(7)E0a
  18. Affected versionversion=15.2(7)E0b
  19. Affected versionversion=15.2(7)E0s
  20. Affected versionversion=15.2(7)E1
  21. Affected versionversion=15.2(7)E10
  22. Affected versionversion=15.2(7)E11
  23. Affected versionversion=15.2(7)E12
  24. Affected versionversion=15.2(7)E1a
  25. Affected versionversion=15.2(7)E2
  26. Affected versionversion=15.2(7)E2a
  27. Affected versionversion=15.2(7)E3
  28. Affected versionversion=15.2(7)E3k
  29. Affected versionversion=15.2(7)E4
  30. Affected versionversion=15.2(7)E5
  31. Affected versionversion=15.2(7)E6
  32. Affected versionversion=15.2(7)E7
  33. Affected versionversion=15.2(7)E8
  34. Affected versionversion=15.2(7)E9
  35. Affected versionversion=15.2(8)E
  36. Affected versionversion=15.2(8)E1
  37. Affected versionversion=15.2(8)E2
  38. Affected versionversion=15.2(8)E3
  39. Affected versionversion=15.2(8)E4
  40. Affected versionversion=15.2(8)E5
  41. Affected versionversion=15.2(8)E6
  42. Affected versionversion=15.2(8)E7
  43. Affected versionversion=15.5(1)SY10
  44. Affected versionversion=15.5(1)SY11
  45. Affected versionversion=15.5(1)SY12
  46. Affected versionversion=15.5(1)SY13
  47. Affected versionversion=15.5(1)SY14
  48. Affected versionversion=15.5(1)SY15
  49. Affected versionversion=15.5(1)SY2
  50. Affected versionversion=15.5(1)SY3
  51. Affected versionversion=15.5(1)SY4
  52. Affected versionversion=15.5(1)SY5
  53. Affected versionversion=15.5(1)SY6
  54. Affected versionversion=15.5(1)SY7
  55. Affected versionversion=15.5(1)SY8
  56. Affected versionversion=15.5(1)SY9
  57. Affected versionversion=15.5(3)M10
  58. Affected versionversion=15.5(3)M7
  59. Affected versionversion=15.5(3)M8
  60. Affected versionversion=15.5(3)M9
  61. Affected versionversion=15.5(3)S10
  62. Affected versionversion=15.5(3)S8
  63. Affected versionversion=15.5(3)S9
  64. Affected versionversion=15.5(3)S9a
  65. Affected versionversion=15.6(2)SP5
  66. Affected versionversion=15.6(2)SP6
  67. Affected versionversion=15.6(2)SP7
  68. Affected versionversion=15.6(2)SP8
  69. Affected versionversion=15.6(2)SP9
  70. Affected versionversion=15.6(3)M4
  71. Affected versionversion=15.6(3)M5
  72. Affected versionversion=15.6(3)M6
  73. Affected versionversion=15.6(3)M6a
  74. Affected versionversion=15.6(3)M6b
  75. Affected versionversion=15.6(3)M7
  76. Affected versionversion=15.6(3)M8
  77. Affected versionversion=15.6(3)M9
  78. Affected versionversion=15.7(3)M2
  79. Affected versionversion=15.7(3)M3
  80. Affected versionversion=15.7(3)M4
  81. Affected versionversion=15.7(3)M4a
  82. Affected versionversion=15.7(3)M4b
  83. Affected versionversion=15.7(3)M5
  84. Affected versionversion=15.7(3)M6
  85. Affected versionversion=15.7(3)M7
  86. Affected versionversion=15.7(3)M8
  87. Affected versionversion=15.7(3)M9
  88. Affected versionversion=15.8(3)M
  89. Affected versionversion=15.8(3)M0a
  90. Affected versionversion=15.8(3)M0b
  91. Affected versionversion=15.8(3)M1
  92. Affected versionversion=15.8(3)M1a
  93. Affected versionversion=15.8(3)M2
  94. Affected versionversion=15.8(3)M2a
  95. Affected versionversion=15.8(3)M3
  96. Affected versionversion=15.8(3)M3a
  97. Affected versionversion=15.8(3)M3b
  98. Affected versionversion=15.8(3)M4
  99. Affected versionversion=15.8(3)M5
  100. Affected versionversion=15.8(3)M6
  101. Affected versionversion=15.8(3)M7
  102. Affected versionversion=15.8(3)M8
  103. Affected versionversion=15.8(3)M9
  104. Affected versionversion=15.9(3)M
  105. Affected versionversion=15.9(3)M0a
  106. Affected versionversion=15.9(3)M1
  107. Affected versionversion=15.9(3)M10
  108. Affected versionversion=15.9(3)M11
  109. Affected versionversion=15.9(3)M2
  110. Affected versionversion=15.9(3)M2a
  111. Affected versionversion=15.9(3)M3
  112. Affected versionversion=15.9(3)M3a
  113. Affected versionversion=15.9(3)M3b
  114. Affected versionversion=15.9(3)M4
  115. Affected versionversion=15.9(3)M4a
  116. Affected versionversion=15.9(3)M5
  117. Affected versionversion=15.9(3)M6
  118. Affected versionversion=15.9(3)M6a
  119. Affected versionversion=15.9(3)M6b
  120. Affected versionversion=15.9(3)M7
  121. Affected versionversion=15.9(3)M7a
  122. Affected versionversion=15.9(3)M8
  123. Affected versionversion=15.9(3)M8b
  124. Affected versionversion=15.9(3)M9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOSversion=15.2(4)E10; version=15.2(4)E10a; version=15.2(4)E10d; version=15.2(4)E6; version=15.2(4)E7; version=15.2(4)E8; version=15.2(4)E9; version=15.2(6)E1; version=15.2(6)E2; version=15.2(6)E2a; version=15.2(6)E2b; version=15.2(6)E3; version=15.2(6)EB; version=15.2(7a)E0b; version=15.2(7b)E0b; version=15.2(7)E; version=15.2(7)E0a; version=15.2(7)E0b; version=15.2(7)E0s; version=15.2(7)E1; version=15.2(7)E10; version=15.2(7)E11; version=15.2(7)E12; version=15.2(7)E1a; version=15.2(7)E2; version=15.2(7)E2a; version=15.2(7)E3; version=15.2(7)E3k; version=15.2(7)E4; version=15.2(7)E5; version=15.2(7)E6; version=15.2(7)E7; version=15.2(7)E8; version=15.2(7)E9; version=15.2(8)E; version=15.2(8)E1; version=15.2(8)E2; version=15.2(8)E3; version=15.2(8)E4; version=15.2(8)E5; version=15.2(8)E6; version=15.2(8)E7; version=15.5(1)SY10; version=15.5(1)SY11; version=15.5(1)SY12; version=15.5(1)SY13; version=15.5(1)SY14; version=15.5(1)SY15; version=15.5(1)SY2; version=15.5(1)SY3; version=15.5(1)SY4; version=15.5(1)SY5; version=15.5(1)SY6; version=15.5(1)SY7; version=15.5(1)SY8; version=15.5(1)SY9; version=15.5(3)M10; version=15.5(3)M7; version=15.5(3)M8; version=15.5(3)M9; version=15.5(3)S10; version=15.5(3)S8; version=15.5(3)S9; version=15.5(3)S9a; version=15.6(2)SP5; version=15.6(2)SP6; version=15.6(2)SP7; version=15.6(2)SP8; version=15.6(2)SP9; version=15.6(3)M4; version=15.6(3)M5; version=15.6(3)M6; version=15.6(3)M6a; version=15.6(3)M6b; version=15.6(3)M7; version=15.6(3)M8; version=15.6(3)M9; version=15.7(3)M2; version=15.7(3)M3; version=15.7(3)M4; version=15.7(3)M4a; version=15.7(3)M4b; version=15.7(3)M5; version=15.7(3)M6; version=15.7(3)M7; version=15.7(3)M8; version=15.7(3)M9; version=15.8(3)M; version=15.8(3)M0a; version=15.8(3)M0b; version=15.8(3)M1; version=15.8(3)M1a; version=15.8(3)M2; version=15.8(3)M2a; version=15.8(3)M3; version=15.8(3)M3a; version=15.8(3)M3b; version=15.8(3)M4; version=15.8(3)M5; version=15.8(3)M6; version=15.8(3)M7; version=15.8(3)M8; version=15.8(3)M9; version=15.9(3)M; version=15.9(3)M0a; version=15.9(3)M1; version=15.9(3)M10; version=15.9(3)M11; version=15.9(3)M2; version=15.9(3)M2a; version=15.9(3)M3; version=15.9(3)M3a; version=15.9(3)M3b; version=15.9(3)M4; version=15.9(3)M4a; version=15.9(3)M5; version=15.9(3)M6; version=15.9(3)M6a; version=15.9(3)M6b; version=15.9(3)M7; version=15.9(3)M7a; version=15.9(3)M8; version=15.9(3)M8b; version=15.9(3)M9
ClamAV · Cisco IOS XE Softwareversion=16.10.1; version=16.10.1a; version=16.10.1b; version=16.10.1c; version=16.10.1d; version=16.10.1e; version=16.10.1f; version=16.10.1g; version=16.10.1s; version=16.10.2; version=16.10.3; version=16.11.1; version=16.11.1a; version=16.11.1b; version=16.11.1s; version=16.11.2; version=16.12.1; version=16.12.10; version=16.12.10a; version=16.12.11; version=16.12.12; version=16.12.13; version=16.12.1a; version=16.12.1c; version=16.12.1s; version=16.12.1t; version=16.12.1w; version=16.12.1x; version=16.12.1y; version=16.12.1z1; version=16.12.1z2; version=16.12.2; version=16.12.2a; version=16.12.2s; version=16.12.3; version=16.12.3a; version=16.12.3s; version=16.12.4; version=16.12.4a; version=16.12.5; version=16.12.5a; version=16.12.5b; version=16.12.6; version=16.12.6a; version=16.12.7; version=16.12.8; version=16.12.9; version=16.6.10; version=16.6.5; version=16.6.5a; version=16.6.6; version=16.6.7; version=16.6.8; version=16.6.9; version=16.8.1; version=16.8.1a; version=16.8.1b; version=16.8.1c; version=16.8.1d; version=16.8.1e; version=16.8.1s; version=16.8.2; version=16.8.3; version=16.9.1; version=16.9.1a; version=16.9.1b; version=16.9.1s; version=16.9.2; version=16.9.3; version=16.9.3a; version=16.9.4; version=16.9.5; version=16.9.5f; version=16.9.6; version=16.9.7; version=16.9.8; version=17.10.1; version=17.10.1a; version=17.10.1b; version=17.1.1; version=17.11.1; version=17.11.1a; version=17.11.99SW; version=17.1.1a; version=17.1.1s; version=17.1.1t; version=17.12.1; version=17.12.1a; version=17.12.1w; version=17.12.1x; version=17.12.1y; version=17.12.1z; version=17.12.1z1; version=17.12.1z2; version=17.12.1z3; version=17.12.1z4; version=17.12.2; version=17.12.2a; version=17.12.3; version=17.12.3a; version=17.12.4; version=17.12.4a; version=17.12.4b; version=17.12.5; version=17.12.5a; version=17.12.5b; version=17.12.5c; version=17.1.3; version=17.13.1; version=17.13.1a; version=17.14.1; version=17.14.1a; version=17.15.1; version=17.15.1a; version=17.15.1b; version=17.15.1w; version=17.15.1x; version=17.15.1y; version=17.15.2; version=17.15.2a; version=17.15.2b; version=17.15.2c; version=17.15.3; version=17.15.3a; version=17.15.3b; version=17.2.1; version=17.2.1a; version=17.2.1r; version=17.2.1v; version=17.2.2; version=17.2.3; version=17.3.1; version=17.3.1a; version=17.3.1w; version=17.3.1x; version=17.3.1z; version=17.3.2; version=17.3.2a; version=17.3.3; version=17.3.4; version=17.3.4a; version=17.3.4b; version=17.3.4c; version=17.3.5; version=17.3.5a; version=17.3.5b; version=17.3.6; version=17.3.7; version=17.3.8; version=17.3.8a; version=17.4.1; version=17.4.1a; version=17.4.1b; version=17.4.2; version=17.4.2a; version=17.5.1; version=17.5.1a; version=17.6.1; version=17.6.1a; version=17.6.1w; version=17.6.1x; version=17.6.1y; version=17.6.1z; version=17.6.1z1; version=17.6.2; version=17.6.3; version=17.6.3a; version=17.6.4; version=17.6.5; version=17.6.5a; version=17.6.6; version=17.6.6a; version=17.6.7; version=17.6.8; version=17.6.8a; version=17.7.1; version=17.7.1a; version=17.7.1b; version=17.7.2; version=17.8.1; version=17.8.1a; version=17.9.1; version=17.9.1a; version=17.9.1w; version=17.9.1x; version=17.9.1x1; version=17.9.1y; version=17.9.1y1; version=17.9.2; version=17.9.2a; version=17.9.3; version=17.9.3a; version=17.9.4; version=17.9.4a; version=17.9.5; version=17.9.5a; version=17.9.5b; version=17.9.5e; version=17.9.5f; version=17.9.6; version=17.9.6a; version=17.9.7; version=17.9.7a; version=17.9.7b; version=3.10.1E; version=3.10.2E; version=3.10.3E; version=3.11.0E; version=3.11.10E; version=3.11.11E; version=3.11.12E; version=3.11.1aE; version=3.11.1E; version=3.11.2E; version=3.11.3aE; version=3.11.3E; version=3.11.4E; version=3.11.5E; version=3.11.6E; version=3.11.7E; version=3.11.8E; version=3.11.9E; version=3.16.10S; version=3.16.8S; version=3.16.9S; version=3.18.5SP; version=3.18.6SP; version=3.18.7SP; version=3.18.8aSP; version=3.18.9SP; version=3.8.10E; version=3.8.6E; version=3.8.7E; version=3.8.8E; version=3.8.9E

Published CVSS scores

8.1Cisco Systems, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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-287Improper Authentication
T1557Adversary-in-the-Middle

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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