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Cisco Bug: CSCup90532 - Cisco IOS and IOS XE Software DNS Forwarder Denial of Service Vulnerability

Last Modified

May 01, 2020

Products (86)

  • Cisco IOS
  • Cisco 886VAG 3G Integrated Services Router
  • Cisco C897VA Integrated Services Router
  • Cisco 2951 Integrated Services Router
  • Cisco 888W Integrated Services Router
  • Cisco 819 Hardened Integrated Services Router
  • Cisco 812 CiFi Integrated Services Router
  • Cisco 861W Integrated Services Router
  • Cisco 1905 Serial Integrated Services Router
  • Cisco 892W Integrated Services Router
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Known Affected Releases


Description (partial)

A vulnerability in the DNS forwarder functionality of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to cause the
device to reload, to corrupt the information present in the device's local DNS cache, or read part of the process memory.

The vulnerability is due to a flaw in handling crafted DNS response messages. An attacker could exploit this vulnerability by intercepting and
crafting a DNS response message to a client DNS query that was forwarded from the affected device to a DNS server. A successful exploit could
cause the device to reload, resulting in a denial of service (DoS) condition or in a corruption of the local DNS cache information.

Cisco has released software updates that address this vulnerability.

This advisory is available at the following link:

See Security Advisory

Related Community Discussions

Cisco PSIRT openVuln API and Cisco IOS Software Checker
The Cisco Product Security Incident Response Team (PSIRT) openVuln API is a RESTful API that allows customers to obtain Cisco Security Vulnerability information in different machine-consumable formats. APIs are important for customers because they allow their technical staff and programmers to build tools that help them do their job more effectively (in this case, to keep up with security vulnerability information). You can use the Cisco PSIRT openVuln API to perform queries similar to the Cisco ...
Latest activity: Jan 11, 2017
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