CVE-2026-20004

Device reload via TLS connection memory exhaustion

Published Mar 25, 2026 · Updated Mar 25, 2026

Resource exhaustion in the TLS library of Cisco IOS XE Software allows attackers on an adjacent network to force an unexpected device reload. The TLS setup path loses track of allocated memory across repeated connection attempts or resets, causing available memory to decline until the device reloads. Exposure requires a nondefault TLS-using feature such as Local EAP, RadSec, SANet, or telemetry, or a man-in-the-middle position able to reset TLS connections; HTTPS web UI traffic is unaffected.

CVSS severity7.4
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in the TLS library of Cisco IOS XE Software allows attackers on an adjacent network to force an unexpected device reload. The TLS setup path loses track of allocated memory across repeated connection attempts or resets, causing available memory to decline until the device reloads. Exposure requires a nondefault TLS-using feature such as Local EAP, RadSec, SANet, or telemetry, or a man-in-the-middle position able to reset TLS connections; HTTPS web UI traffic is unaffected.

The record

CVE
CVE-2026-20004
Published
Mar 25, 2026
Updated
Mar 25, 2026
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-771, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 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=16.10.1
  2. Affected versionversion=16.10.1a
  3. Affected versionversion=16.10.1b
  4. Affected versionversion=16.10.1c
  5. Affected versionversion=16.10.1d
  6. Affected versionversion=16.10.1e
  7. Affected versionversion=16.10.1f
  8. Affected versionversion=16.10.1g
  9. Affected versionversion=16.10.1s
  10. Affected versionversion=16.10.2
  11. Affected versionversion=16.10.3
  12. Affected versionversion=16.11.1
  13. Affected versionversion=16.11.1a
  14. Affected versionversion=16.11.1b
  15. Affected versionversion=16.11.1s
  16. Affected versionversion=16.11.2
  17. Affected versionversion=16.12.1
  18. Affected versionversion=16.12.10
  19. Affected versionversion=16.12.10a
  20. Affected versionversion=16.12.11
  21. Affected versionversion=16.12.12
  22. Affected versionversion=16.12.13
  23. Affected versionversion=16.12.14
  24. Affected versionversion=16.12.15
  25. Affected versionversion=16.12.1a
  26. Affected versionversion=16.12.1c
  27. Affected versionversion=16.12.1s
  28. Affected versionversion=16.12.1t
  29. Affected versionversion=16.12.1w
  30. Affected versionversion=16.12.1x
  31. Affected versionversion=16.12.1y
  32. Affected versionversion=16.12.1z1
  33. Affected versionversion=16.12.1z2
  34. Affected versionversion=16.12.2
  35. Affected versionversion=16.12.2a
  36. Affected versionversion=16.12.2s
  37. Affected versionversion=16.12.3
  38. Affected versionversion=16.12.3a
  39. Affected versionversion=16.12.3s
  40. Affected versionversion=16.12.4
  41. Affected versionversion=16.12.4a
  42. Affected versionversion=16.12.5
  43. Affected versionversion=16.12.5a
  44. Affected versionversion=16.12.5b
  45. Affected versionversion=16.12.6
  46. Affected versionversion=16.12.6a
  47. Affected versionversion=16.12.7
  48. Affected versionversion=16.12.8
  49. Affected versionversion=16.12.9
  50. Affected versionversion=16.9.1
  51. Affected versionversion=16.9.1a
  52. Affected versionversion=16.9.1b
  53. Affected versionversion=16.9.1s
  54. Affected versionversion=16.9.2
  55. Affected versionversion=16.9.3
  56. Affected versionversion=16.9.3a
  57. Affected versionversion=16.9.4
  58. Affected versionversion=16.9.5
  59. Affected versionversion=16.9.5f
  60. Affected versionversion=16.9.6
  61. Affected versionversion=16.9.7
  62. Affected versionversion=16.9.8
  63. Affected versionversion=17.10.1
  64. Affected versionversion=17.10.1a
  65. Affected versionversion=17.10.1b
  66. Affected versionversion=17.1.1
  67. Affected versionversion=17.11.1
  68. Affected versionversion=17.11.1a
  69. Affected versionversion=17.1.1a
  70. Affected versionversion=17.1.1s
  71. Affected versionversion=17.1.1t
  72. Affected versionversion=17.12.1
  73. Affected versionversion=17.12.1a
  74. Affected versionversion=17.12.1w
  75. Affected versionversion=17.12.1x
  76. Affected versionversion=17.12.1y
  77. Affected versionversion=17.12.1z
  78. Affected versionversion=17.12.1z1
  79. Affected versionversion=17.12.1z2
  80. Affected versionversion=17.12.1z3
  81. Affected versionversion=17.12.1z4
  82. Affected versionversion=17.12.1z5
  83. Affected versionversion=17.12.1z6
  84. Affected versionversion=17.12.2
  85. Affected versionversion=17.12.2a
  86. Affected versionversion=17.12.3
  87. Affected versionversion=17.12.3a
  88. Affected versionversion=17.12.4
  89. Affected versionversion=17.12.4a
  90. Affected versionversion=17.12.4b
  91. Affected versionversion=17.1.3
  92. Affected versionversion=17.13.1
  93. Affected versionversion=17.13.1a
  94. Affected versionversion=17.14.1
  95. Affected versionversion=17.14.1a
  96. Affected versionversion=17.15.1
  97. Affected versionversion=17.15.1a
  98. Affected versionversion=17.15.1b
  99. Affected versionversion=17.15.1w
  100. Affected versionversion=17.15.1x
  101. Affected versionversion=17.15.1y
  102. Affected versionversion=17.15.1z
  103. Affected versionversion=17.16.1
  104. Affected versionversion=17.16.1a
  105. Affected versionversion=17.2.1
  106. Affected versionversion=17.2.1a
  107. Affected versionversion=17.2.1r
  108. Affected versionversion=17.2.1v
  109. Affected versionversion=17.2.2
  110. Affected versionversion=17.2.3
  111. Affected versionversion=17.3.1
  112. Affected versionversion=17.3.1a
  113. Affected versionversion=17.3.1w
  114. Affected versionversion=17.3.1x
  115. Affected versionversion=17.3.1z
  116. Affected versionversion=17.3.2
  117. Affected versionversion=17.3.2a
  118. Affected versionversion=17.3.3
  119. Affected versionversion=17.3.4
  120. Affected versionversion=17.3.4a
  121. Affected versionversion=17.3.4b
  122. Affected versionversion=17.3.4c
  123. Affected versionversion=17.3.5
  124. Affected versionversion=17.3.5a
  125. Affected versionversion=17.3.5b
  126. Affected versionversion=17.3.6
  127. Affected versionversion=17.3.7
  128. Affected versionversion=17.3.8
  129. Affected versionversion=17.3.8a
  130. Affected versionversion=17.4.1
  131. Affected versionversion=17.4.1a
  132. Affected versionversion=17.4.1b
  133. Affected versionversion=17.4.2
  134. Affected versionversion=17.4.2a
  135. Affected versionversion=17.5.1
  136. Affected versionversion=17.5.1a
  137. Affected versionversion=17.6.1
  138. Affected versionversion=17.6.1a
  139. Affected versionversion=17.6.1w
  140. Affected versionversion=17.6.1x
  141. Affected versionversion=17.6.1y
  142. Affected versionversion=17.6.1z
  143. Affected versionversion=17.6.1z1
  144. Affected versionversion=17.6.2
  145. Affected versionversion=17.6.3
  146. Affected versionversion=17.6.3a
  147. Affected versionversion=17.6.4
  148. Affected versionversion=17.6.5
  149. Affected versionversion=17.6.5a
  150. Affected versionversion=17.6.6
  151. Affected versionversion=17.6.6a
  152. Affected versionversion=17.6.7
  153. Affected versionversion=17.6.8
  154. Affected versionversion=17.6.8a
  155. Affected versionversion=17.7.1
  156. Affected versionversion=17.7.1a
  157. Affected versionversion=17.7.1b
  158. Affected versionversion=17.7.2
  159. Affected versionversion=17.8.1
  160. Affected versionversion=17.8.1a
  161. Affected versionversion=17.9.1
  162. Affected versionversion=17.9.1a
  163. Affected versionversion=17.9.1w
  164. Affected versionversion=17.9.1x
  165. Affected versionversion=17.9.1x1
  166. Affected versionversion=17.9.1y
  167. Affected versionversion=17.9.1y1
  168. Affected versionversion=17.9.2
  169. Affected versionversion=17.9.2a
  170. Affected versionversion=17.9.3
  171. Affected versionversion=17.9.3a
  172. Affected versionversion=17.9.4
  173. Affected versionversion=17.9.4a
  174. Affected versionversion=17.9.5
  175. Affected versionversion=17.9.5a
  176. Affected versionversion=17.9.5b
  177. Affected versionversion=17.9.5e
  178. Affected versionversion=17.9.5f
  179. Affected versionversion=17.9.6
  180. Affected versionversion=17.9.6a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

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=16.12.14; version=16.12.15; 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=16.9.1; 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=17.1.1a; 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=17.12.1z5; 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=17.1.3; 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=17.15.1z; version=17.16.1; version=17.16.1a; 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

Published CVSS scores

7.4Cisco Systems, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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-771Missing Reference to Active Allocated Resource
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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