CVE-2026-20311Network attack vector

Authenticated device reload via malformed PIV certificate

Published Aug 5, 2026 · Updated Aug 5, 2026

Buffer over-read in Cisco IOS XE Software allows remote authenticated users to reload affected devices via a malformed PIV certificate. The web-based management interface insufficiently handles an error while authenticating the malformed certificate, which triggers the device reload. Exploitation requires a low-privileged account, a vulnerable release, and both the HTTP Server and PIV features enabled; the resulting interruption lasts until the device finishes reloading.

CVSS severity6.3
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Buffer over-read in Cisco IOS XE Software allows remote authenticated users to reload affected devices via a malformed PIV certificate. The web-based management interface insufficiently handles an error while authenticating the malformed certificate, which triggers the device reload. Exploitation requires a low-privileged account, a vulnerable release, and both the HTTP Server and PIV features enabled; the resulting interruption lasts until the device finishes reloading.

The record

CVE
CVE-2026-20311
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-126, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=17.10.1
  2. Affected versionversion=17.10.1a
  3. Affected versionversion=17.10.1b
  4. Affected versionversion=17.11.1
  5. Affected versionversion=17.11.1a
  6. Affected versionversion=17.12.1
  7. Affected versionversion=17.12.1a
  8. Affected versionversion=17.12.1w
  9. Affected versionversion=17.12.1x
  10. Affected versionversion=17.12.1y
  11. Affected versionversion=17.12.1z
  12. Affected versionversion=17.12.1z1
  13. Affected versionversion=17.12.1z2
  14. Affected versionversion=17.12.1z3
  15. Affected versionversion=17.12.1z4
  16. Affected versionversion=17.12.1z5
  17. Affected versionversion=17.12.1z6
  18. Affected versionversion=17.12.2
  19. Affected versionversion=17.12.2a
  20. Affected versionversion=17.12.3
  21. Affected versionversion=17.12.3a
  22. Affected versionversion=17.12.4
  23. Affected versionversion=17.12.4a
  24. Affected versionversion=17.12.4b
  25. Affected versionversion=17.12.5
  26. Affected versionversion=17.12.5a
  27. Affected versionversion=17.12.5b
  28. Affected versionversion=17.12.5c
  29. Affected versionversion=17.12.5d
  30. Affected versionversion=17.12.6
  31. Affected versionversion=17.12.6a
  32. Affected versionversion=17.12.6b
  33. Affected versionversion=17.12.7
  34. Affected versionversion=17.12.7a
  35. Affected versionversion=17.12.7b
  36. Affected versionversion=17.13.1
  37. Affected versionversion=17.13.1a
  38. Affected versionversion=17.14.1
  39. Affected versionversion=17.14.1a
  40. Affected versionversion=17.15.1
  41. Affected versionversion=17.15.1a
  42. Affected versionversion=17.15.1b
  43. Affected versionversion=17.15.1w
  44. Affected versionversion=17.15.1x
  45. Affected versionversion=17.15.1y
  46. Affected versionversion=17.15.2
  47. Affected versionversion=17.15.2a
  48. Affected versionversion=17.15.2b
  49. Affected versionversion=17.15.2c
  50. Affected versionversion=17.15.3
  51. Affected versionversion=17.15.3a
  52. Affected versionversion=17.15.3b
  53. Affected versionversion=17.15.4
  54. Affected versionversion=17.15.4a
  55. Affected versionversion=17.15.4b
  56. Affected versionversion=17.15.4c
  57. Affected versionversion=17.15.4d
  58. Affected versionversion=17.15.4s1
  59. Affected versionversion=17.15.5
  60. Affected versionversion=17.15.5a
  61. Affected versionversion=17.16.1
  62. Affected versionversion=17.16.1a
  63. Affected versionversion=17.17.1
  64. Affected versionversion=17.18.1
  65. Affected versionversion=17.18.1a
  66. Affected versionversion=17.18.1w
  67. Affected versionversion=17.18.1x
  68. Affected versionversion=17.18.1y
  69. Affected versionversion=17.18.1z
  70. Affected versionversion=17.18.2
  71. Affected versionversion=17.18.3
  72. Affected versionversion=17.18.3a
  73. Affected versionversion=17.3.1
  74. Affected versionversion=17.3.1a
  75. Affected versionversion=17.3.1w
  76. Affected versionversion=17.3.1x
  77. Affected versionversion=17.3.1z
  78. Affected versionversion=17.3.2
  79. Affected versionversion=17.3.2a
  80. Affected versionversion=17.3.3
  81. Affected versionversion=17.3.3a
  82. Affected versionversion=17.3.4
  83. Affected versionversion=17.3.4a
  84. Affected versionversion=17.3.4b
  85. Affected versionversion=17.3.4c
  86. Affected versionversion=17.3.5
  87. Affected versionversion=17.3.5a
  88. Affected versionversion=17.3.5b
  89. Affected versionversion=17.3.6
  90. Affected versionversion=17.3.7
  91. Affected versionversion=17.3.8
  92. Affected versionversion=17.3.8a
  93. Affected versionversion=17.4.1
  94. Affected versionversion=17.4.1a
  95. Affected versionversion=17.4.1b
  96. Affected versionversion=17.4.1c
  97. Affected versionversion=17.4.2
  98. Affected versionversion=17.4.2a
  99. Affected versionversion=17.5.1
  100. Affected versionversion=17.5.1a
  101. Affected versionversion=17.6.1
  102. Affected versionversion=17.6.1a
  103. Affected versionversion=17.6.1x
  104. Affected versionversion=17.6.1z
  105. Affected versionversion=17.6.1z1
  106. Affected versionversion=17.6.2
  107. Affected versionversion=17.6.3
  108. Affected versionversion=17.6.3a
  109. Affected versionversion=17.6.4
  110. Affected versionversion=17.6.5
  111. Affected versionversion=17.6.5a
  112. Affected versionversion=17.6.6
  113. Affected versionversion=17.6.6a
  114. Affected versionversion=17.6.7
  115. Affected versionversion=17.6.8
  116. Affected versionversion=17.6.8a
  117. Affected versionversion=17.7.1
  118. Affected versionversion=17.7.1a
  119. Affected versionversion=17.7.1b
  120. Affected versionversion=17.7.2
  121. Affected versionversion=17.8.1
  122. Affected versionversion=17.8.1a
  123. Affected versionversion=17.9.1
  124. Affected versionversion=17.9.1a
  125. Affected versionversion=17.9.1w
  126. Affected versionversion=17.9.1x
  127. Affected versionversion=17.9.1x1
  128. Affected versionversion=17.9.1y
  129. Affected versionversion=17.9.1y1
  130. Affected versionversion=17.9.2
  131. Affected versionversion=17.9.2a
  132. Affected versionversion=17.9.3
  133. Affected versionversion=17.9.3a
  134. Affected versionversion=17.9.4
  135. Affected versionversion=17.9.4a
  136. Affected versionversion=17.9.5
  137. Affected versionversion=17.9.5a
  138. Affected versionversion=17.9.5b
  139. Affected versionversion=17.9.5c
  140. Affected versionversion=17.9.5d
  141. Affected versionversion=17.9.5e
  142. Affected versionversion=17.9.5f
  143. Affected versionversion=17.9.6
  144. Affected versionversion=17.9.6a
  145. Affected versionversion=17.9.7
  146. Affected versionversion=17.9.7a
  147. Affected versionversion=17.9.7b
  148. Affected versionversion=17.9.8
  149. Affected versionversion=17.9.9
  150. Affected versionversion=26.1.1
  151. Affected versionversion=26.1.1a
  152. Affected versionversion=26.2.1ea

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ClamAV · Cisco IOS XE Softwareversion=17.10.1; version=17.10.1a; version=17.10.1b; version=17.11.1; version=17.11.1a; 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=17.12.1z5; version=17.12.1z6; 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=17.12.5d; version=17.12.6; version=17.12.6a; version=17.12.6b; version=17.12.7; version=17.12.7a; version=17.12.7b; 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=17.15.4; version=17.15.4a; version=17.15.4b; version=17.15.4c; version=17.15.4d; version=17.15.4s1; version=17.15.5; version=17.15.5a; version=17.16.1; version=17.16.1a; version=17.17.1; version=17.18.1; version=17.18.1a; version=17.18.1w; version=17.18.1x; version=17.18.1y; version=17.18.1z; version=17.18.2; version=17.18.3; version=17.18.3a; 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=17.3.3a; 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=17.4.1c; 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=17.6.1x; 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=17.9.5c; version=17.9.5d; 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=17.9.8; version=17.9.9; version=26.1.1; version=26.1.1a; version=26.2.1ea

Published CVSS scores

6.3CiscoCVSS:3.1/AV:N/AC:H/PR:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-126Buffer Over-read
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo