Executive Summary

Title Cisco Web Security Appliance Connection Denial of Service Vulnerability
Name cisco-sa-20160518-wsa4 First vendor Publication 2016-05-18
Vendor Cisco Last vendor Modification 2016-05-18
Severity (Vendor) N/A Revision 1.0

Security-Database Scoring CVSS v3

Cvss vector : N/A
Overall CVSS Score NA
Base Score NA Environmental Score NA
impact SubScore NA Temporal Score NA
Exploitabality Sub Score NA
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector : (AV:N/AC:L/Au:N/C:N/I:N/A:C)
Cvss Base Score 7.8 Attack Range Network
Cvss Impact Score 6.9 Attack Complexity Low
Cvss Expoit Score 10 Authentication None Required
Calculate full CVSS 2.0 Vectors scores


A vulnerability in Cisco AsyncOS for the Cisco Web Security Appliance (WSA) when the software handles a specific HTTP response code could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an appliance because the appliance runs out of system memory.

The vulnerability occurs because the software does not free client and server connection memory and system file descriptors when a certain HTTP response code is received in the HTTP request. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. An exploit could allow the attacker to cause a DoS condition because the appliance runs out of system memory. When this happens, the device can no longer accept new incoming connection requests.

Cisco has released software updates that address this vulnerability. A workaround that addresses this vulnerability is also available. This advisory is available at the following link:


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Original Source

Url : http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco (...)

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-399 Resource Management Errors

CPE : Common Platform Enumeration

Application 27

Snort® IPS/IDS

Date Description
2016-05-19 Cisco Web Security Appliance socket exhaustion denial of service attempt
RuleID : 38958 - Revision : 1 - Type : SERVER-OTHER

Nessus® Vulnerability Scanner

Date Description
2016-05-26 Name : The remote security appliance is missing a vendor-supplied patch.
File : cisco-sa-20160518-wsa1_to_wsa4.nasl - Type : ACT_GATHER_INFO

Alert History

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Date Informations
2016-05-27 13:27:33
  • Multiple Updates
2016-05-26 00:34:36
  • Multiple Updates
2016-05-18 21:24:20
  • First insertion