CVE-2025-20135

Service interruption via DHCPv4 memory exhaustion

Published Aug 14, 2025 · Updated Aug 14, 2025

Denial of service in Cisco Secure Firewall ASA and FTD Software allows attackers to exhaust memory with crafted DHCPv4 packets. The DHCP client improperly validates repeatedly received packets and retains allocations until available memory is exhausted, preventing new processes from starting. Exploitation requires adjacent access and DHCP client enablement; services remain impaired until a manual reboot, and FTD management interfaces are excluded.

CVSS severity4.3
Medium
EPSS probability0.20%
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 Cisco Secure Firewall ASA and FTD Software allows attackers to exhaust memory with crafted DHCPv4 packets. The DHCP client improperly validates repeatedly received packets and retains allocations until available memory is exhausted, preventing new processes from starting. Exploitation requires adjacent access and DHCP client enablement; services remain impaired until a manual reboot, and FTD management interfaces are excluded.

The record

CVE
CVE-2025-20135
Published
Aug 14, 2025
Updated
Aug 14, 2025
Vendor
ClamAV
Product
Cisco Adaptive Security Appliance (ASA) Software
Classifications
CWE-401, T1499.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 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=9.12.1
  2. Affected versionversion=9.12.1.2
  3. Affected versionversion=9.12.1.3
  4. Affected versionversion=9.12.2
  5. Affected versionversion=9.12.2.1
  6. Affected versionversion=9.12.2.4
  7. Affected versionversion=9.12.2.5
  8. Affected versionversion=9.12.2.9
  9. Affected versionversion=9.12.3
  10. Affected versionversion=9.12.3.12
  11. Affected versionversion=9.12.3.2
  12. Affected versionversion=9.12.3.7
  13. Affected versionversion=9.12.3.9
  14. Affected versionversion=9.12.4
  15. Affected versionversion=9.12.4.10
  16. Affected versionversion=9.12.4.13
  17. Affected versionversion=9.12.4.18
  18. Affected versionversion=9.12.4.2
  19. Affected versionversion=9.12.4.24
  20. Affected versionversion=9.12.4.26
  21. Affected versionversion=9.12.4.29
  22. Affected versionversion=9.12.4.30
  23. Affected versionversion=9.12.4.35
  24. Affected versionversion=9.12.4.37
  25. Affected versionversion=9.12.4.38
  26. Affected versionversion=9.12.4.39
  27. Affected versionversion=9.12.4.4
  28. Affected versionversion=9.12.4.40
  29. Affected versionversion=9.12.4.41
  30. Affected versionversion=9.12.4.47
  31. Affected versionversion=9.12.4.48
  32. Affected versionversion=9.12.4.50
  33. Affected versionversion=9.12.4.52
  34. Affected versionversion=9.12.4.54
  35. Affected versionversion=9.12.4.55
  36. Affected versionversion=9.12.4.56
  37. Affected versionversion=9.12.4.58
  38. Affected versionversion=9.12.4.62
  39. Affected versionversion=9.12.4.65
  40. Affected versionversion=9.12.4.67
  41. Affected versionversion=9.12.4.7
  42. Affected versionversion=9.12.4.8
  43. Affected versionversion=9.14.1
  44. Affected versionversion=9.14.1.10
  45. Affected versionversion=9.14.1.15
  46. Affected versionversion=9.14.1.19
  47. Affected versionversion=9.14.1.30
  48. Affected versionversion=9.14.1.6
  49. Affected versionversion=9.14.2
  50. Affected versionversion=9.14.2.13
  51. Affected versionversion=9.14.2.15
  52. Affected versionversion=9.14.2.4
  53. Affected versionversion=9.14.2.8
  54. Affected versionversion=9.14.3
  55. Affected versionversion=9.14.3.1
  56. Affected versionversion=9.14.3.11
  57. Affected versionversion=9.14.3.13
  58. Affected versionversion=9.14.3.15
  59. Affected versionversion=9.14.3.18
  60. Affected versionversion=9.14.3.9
  61. Affected versionversion=9.14.4
  62. Affected versionversion=9.14.4.12
  63. Affected versionversion=9.14.4.13
  64. Affected versionversion=9.14.4.14
  65. Affected versionversion=9.14.4.15
  66. Affected versionversion=9.14.4.17
  67. Affected versionversion=9.14.4.22
  68. Affected versionversion=9.14.4.23
  69. Affected versionversion=9.14.4.24
  70. Affected versionversion=9.14.4.6
  71. Affected versionversion=9.14.4.7
  72. Affected versionversion=9.15.1.1
  73. Affected versionversion=9.16.1
  74. Affected versionversion=9.16.1.28
  75. Affected versionversion=9.16.2
  76. Affected versionversion=9.16.2.11
  77. Affected versionversion=9.16.2.13
  78. Affected versionversion=9.16.2.14
  79. Affected versionversion=9.16.2.3
  80. Affected versionversion=9.16.2.7
  81. Affected versionversion=9.16.3
  82. Affected versionversion=9.16.3.14
  83. Affected versionversion=9.16.3.15
  84. Affected versionversion=9.16.3.19
  85. Affected versionversion=9.16.3.23
  86. Affected versionversion=9.16.3.3
  87. Affected versionversion=9.16.4
  88. Affected versionversion=9.16.4.14
  89. Affected versionversion=9.16.4.18
  90. Affected versionversion=9.16.4.19
  91. Affected versionversion=9.16.4.27
  92. Affected versionversion=9.16.4.38
  93. Affected versionversion=9.16.4.39
  94. Affected versionversion=9.16.4.42
  95. Affected versionversion=9.16.4.48
  96. Affected versionversion=9.16.4.55
  97. Affected versionversion=9.16.4.57
  98. Affected versionversion=9.16.4.61
  99. Affected versionversion=9.16.4.62
  100. Affected versionversion=9.16.4.67
  101. Affected versionversion=9.16.4.70
  102. Affected versionversion=9.16.4.71
  103. Affected versionversion=9.16.4.9
  104. Affected versionversion=9.17.1
  105. Affected versionversion=9.17.1.10
  106. Affected versionversion=9.17.1.11
  107. Affected versionversion=9.17.1.13
  108. Affected versionversion=9.17.1.15
  109. Affected versionversion=9.17.1.20
  110. Affected versionversion=9.17.1.30
  111. Affected versionversion=9.17.1.33
  112. Affected versionversion=9.17.1.39
  113. Affected versionversion=9.17.1.45
  114. Affected versionversion=9.17.1.46
  115. Affected versionversion=9.17.1.7
  116. Affected versionversion=9.17.1.9
  117. Affected versionversion=9.18.1
  118. Affected versionversion=9.18.1.3
  119. Affected versionversion=9.18.2
  120. Affected versionversion=9.18.2.5
  121. Affected versionversion=9.18.2.7
  122. Affected versionversion=9.18.2.8
  123. Affected versionversion=9.18.3
  124. Affected versionversion=9.18.3.39
  125. Affected versionversion=9.18.3.46
  126. Affected versionversion=9.18.3.53
  127. Affected versionversion=9.18.3.55
  128. Affected versionversion=9.18.3.56
  129. Affected versionversion=9.18.4
  130. Affected versionversion=9.18.4.22
  131. Affected versionversion=9.18.4.24
  132. Affected versionversion=9.18.4.29
  133. Affected versionversion=9.18.4.34
  134. Affected versionversion=9.18.4.40
  135. Affected versionversion=9.18.4.47
  136. Affected versionversion=9.18.4.5
  137. Affected versionversion=9.18.4.8
  138. Affected versionversion=9.19.1
  139. Affected versionversion=9.19.1.12
  140. Affected versionversion=9.19.1.18
  141. Affected versionversion=9.19.1.22
  142. Affected versionversion=9.19.1.24
  143. Affected versionversion=9.19.1.27
  144. Affected versionversion=9.19.1.28
  145. Affected versionversion=9.19.1.31
  146. Affected versionversion=9.19.1.37
  147. Affected versionversion=9.19.1.38
  148. Affected versionversion=9.19.1.5
  149. Affected versionversion=9.19.1.9
  150. Affected versionversion=9.20.1
  151. Affected versionversion=9.20.1.5
  152. Affected versionversion=9.20.2
  153. Affected versionversion=9.20.2.10
  154. Affected versionversion=9.20.2.21
  155. Affected versionversion=9.20.2.22
  156. Affected versionversion=9.20.3
  157. Affected versionversion=9.20.3.4
  158. Affected versionversion=9.22.1.1
  159. Affected versionversion=9.22.1.2
  160. Affected versionversion=9.8.1
  161. Affected versionversion=9.8.1.5
  162. Affected versionversion=9.8.1.7
  163. Affected versionversion=9.8.2
  164. Affected versionversion=9.8.2.14
  165. Affected versionversion=9.8.2.15
  166. Affected versionversion=9.8.2.17
  167. Affected versionversion=9.8.2.20
  168. Affected versionversion=9.8.2.24
  169. Affected versionversion=9.8.2.26
  170. Affected versionversion=9.8.2.28
  171. Affected versionversion=9.8.2.33
  172. Affected versionversion=9.8.2.35
  173. Affected versionversion=9.8.2.38
  174. Affected versionversion=9.8.2.45
  175. Affected versionversion=9.8.2.8
  176. Affected versionversion=9.8.3
  177. Affected versionversion=9.8.3.11
  178. Affected versionversion=9.8.3.14
  179. Affected versionversion=9.8.3.16
  180. Affected versionversion=9.8.3.18
  181. Affected versionversion=9.8.3.21
  182. Affected versionversion=9.8.3.26
  183. Affected versionversion=9.8.3.29
  184. Affected versionversion=9.8.3.8
  185. Affected versionversion=9.8.4
  186. Affected versionversion=9.8.4.10
  187. Affected versionversion=9.8.4.12
  188. Affected versionversion=9.8.4.15
  189. Affected versionversion=9.8.4.17
  190. Affected versionversion=9.8.4.20
  191. Affected versionversion=9.8.4.22
  192. Affected versionversion=9.8.4.25
  193. Affected versionversion=9.8.4.26
  194. Affected versionversion=9.8.4.29
  195. Affected versionversion=9.8.4.3
  196. Affected versionversion=9.8.4.32
  197. Affected versionversion=9.8.4.33
  198. Affected versionversion=9.8.4.34
  199. Affected versionversion=9.8.4.35
  200. Affected versionversion=9.8.4.39
  201. Affected versionversion=9.8.4.40
  202. Affected versionversion=9.8.4.41
  203. Affected versionversion=9.8.4.43
  204. Affected versionversion=9.8.4.44
  205. Affected versionversion=9.8.4.45
  206. Affected versionversion=9.8.4.46
  207. Affected versionversion=9.8.4.48
  208. Affected versionversion=9.8.4.7
  209. Affected versionversion=9.8.4.8

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Adaptive Security Appliance (ASA) Softwareversion=9.12.1; version=9.12.1.2; version=9.12.1.3; version=9.12.2; version=9.12.2.1; version=9.12.2.4; version=9.12.2.5; version=9.12.2.9; version=9.12.3; version=9.12.3.12; version=9.12.3.2; version=9.12.3.7; version=9.12.3.9; version=9.12.4; version=9.12.4.10; version=9.12.4.13; version=9.12.4.18; version=9.12.4.2; version=9.12.4.24; version=9.12.4.26; version=9.12.4.29; version=9.12.4.30; version=9.12.4.35; version=9.12.4.37; version=9.12.4.38; version=9.12.4.39; version=9.12.4.4; version=9.12.4.40; version=9.12.4.41; version=9.12.4.47; version=9.12.4.48; version=9.12.4.50; version=9.12.4.52; version=9.12.4.54; version=9.12.4.55; version=9.12.4.56; version=9.12.4.58; version=9.12.4.62; version=9.12.4.65; version=9.12.4.67; version=9.12.4.7; version=9.12.4.8; version=9.14.1; version=9.14.1.10; version=9.14.1.15; version=9.14.1.19; version=9.14.1.30; version=9.14.1.6; version=9.14.2; version=9.14.2.13; version=9.14.2.15; version=9.14.2.4; version=9.14.2.8; version=9.14.3; version=9.14.3.1; version=9.14.3.11; version=9.14.3.13; version=9.14.3.15; version=9.14.3.18; version=9.14.3.9; version=9.14.4; version=9.14.4.12; version=9.14.4.13; version=9.14.4.14; version=9.14.4.15; version=9.14.4.17; version=9.14.4.22; version=9.14.4.23; version=9.14.4.24; version=9.14.4.6; version=9.14.4.7; version=9.15.1.1; version=9.16.1; version=9.16.1.28; version=9.16.2; version=9.16.2.11; version=9.16.2.13; version=9.16.2.14; version=9.16.2.3; version=9.16.2.7; version=9.16.3; version=9.16.3.14; version=9.16.3.15; version=9.16.3.19; version=9.16.3.23; version=9.16.3.3; version=9.16.4; version=9.16.4.14; version=9.16.4.18; version=9.16.4.19; version=9.16.4.27; version=9.16.4.38; version=9.16.4.39; version=9.16.4.42; version=9.16.4.48; version=9.16.4.55; version=9.16.4.57; version=9.16.4.61; version=9.16.4.62; version=9.16.4.67; version=9.16.4.70; version=9.16.4.71; version=9.16.4.9; version=9.17.1; version=9.17.1.10; version=9.17.1.11; version=9.17.1.13; version=9.17.1.15; version=9.17.1.20; version=9.17.1.30; version=9.17.1.33; version=9.17.1.39; version=9.17.1.45; version=9.17.1.46; version=9.17.1.7; version=9.17.1.9; version=9.18.1; version=9.18.1.3; version=9.18.2; version=9.18.2.5; version=9.18.2.7; version=9.18.2.8; version=9.18.3; version=9.18.3.39; version=9.18.3.46; version=9.18.3.53; version=9.18.3.55; version=9.18.3.56; version=9.18.4; version=9.18.4.22; version=9.18.4.24; version=9.18.4.29; version=9.18.4.34; version=9.18.4.40; version=9.18.4.47; version=9.18.4.5; version=9.18.4.8; version=9.19.1; version=9.19.1.12; version=9.19.1.18; version=9.19.1.22; version=9.19.1.24; version=9.19.1.27; version=9.19.1.28; version=9.19.1.31; version=9.19.1.37; version=9.19.1.38; version=9.19.1.5; version=9.19.1.9; version=9.20.1; version=9.20.1.5; version=9.20.2; version=9.20.2.10; version=9.20.2.21; version=9.20.2.22; version=9.20.3; version=9.20.3.4; version=9.22.1.1; version=9.22.1.2; version=9.8.1; version=9.8.1.5; version=9.8.1.7; version=9.8.2; version=9.8.2.14; version=9.8.2.15; version=9.8.2.17; version=9.8.2.20; version=9.8.2.24; version=9.8.2.26; version=9.8.2.28; version=9.8.2.33; version=9.8.2.35; version=9.8.2.38; version=9.8.2.45; version=9.8.2.8; version=9.8.3; version=9.8.3.11; version=9.8.3.14; version=9.8.3.16; version=9.8.3.18; version=9.8.3.21; version=9.8.3.26; version=9.8.3.29; version=9.8.3.8; version=9.8.4; version=9.8.4.10; version=9.8.4.12; version=9.8.4.15; version=9.8.4.17; version=9.8.4.20; version=9.8.4.22; version=9.8.4.25; version=9.8.4.26; version=9.8.4.29; version=9.8.4.3; version=9.8.4.32; version=9.8.4.33; version=9.8.4.34; version=9.8.4.35; version=9.8.4.39; version=9.8.4.40; version=9.8.4.41; version=9.8.4.43; version=9.8.4.44; version=9.8.4.45; version=9.8.4.46; version=9.8.4.48; version=9.8.4.7; version=9.8.4.8
ClamAV · Cisco Firepower Threat Defenseversion=6.2.3; version=6.2.3.1; version=6.2.3.10; version=6.2.3.11; version=6.2.3.12; version=6.2.3.13; version=6.2.3.14; version=6.2.3.15; version=6.2.3.16; version=6.2.3.17; version=6.2.3.18; version=6.2.3.2; version=6.2.3.3; version=6.2.3.4; version=6.2.3.5; version=6.2.3.6; version=6.2.3.7; version=6.2.3.8; version=6.2.3.9; version=6.4.0; version=6.4.0.1; version=6.4.0.10; version=6.4.0.11; version=6.4.0.12; version=6.4.0.13; version=6.4.0.14; version=6.4.0.15; version=6.4.0.16; version=6.4.0.17; version=6.4.0.18; version=6.4.0.2; version=6.4.0.3; version=6.4.0.4; version=6.4.0.5; version=6.4.0.6; version=6.4.0.7; version=6.4.0.8; version=6.4.0.9; version=6.6.0; version=6.6.0.1; version=6.6.1; version=6.6.3; version=6.6.4; version=6.6.5; version=6.6.5.1; version=6.6.5.2; version=6.6.7; version=6.6.7.1; version=6.6.7.2; version=7.0.0; version=7.0.0.1; version=7.0.1; version=7.0.1.1; version=7.0.2; version=7.0.2.1; version=7.0.3; version=7.0.4; version=7.0.5; version=7.0.6; version=7.0.6.1; version=7.0.6.2; version=7.0.6.3; version=7.1.0; version=7.1.0.1; version=7.1.0.2; version=7.1.0.3; version=7.2.0; version=7.2.0.1; version=7.2.1; version=7.2.2; version=7.2.3; version=7.2.4; version=7.2.4.1; version=7.2.5; version=7.2.5.1; version=7.2.5.2; version=7.2.6; version=7.2.7; version=7.2.8; version=7.2.8.1; version=7.2.9; version=7.3.0; version=7.3.1; version=7.3.1.1; version=7.3.1.2; version=7.4.0; version=7.4.1; version=7.4.1.1; version=7.4.2; version=7.4.2.1; version=7.6.0

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/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.002Service Exhaustion Flood

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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