Cisco Releases Patches 3 New Critical Flaws Affecting IOS XE Software

Networking equipment maker Cisco Systems has rolled out patches
to address three critical security vulnerabilities in its IOS XE
network operating system that remote attackers could potentially
abuse to execute arbitrary code with administrative privileges and
trigger a denial-of-service (DoS) condition on vulnerable
devices.

The list of three flaws is as follows –

• CVE-2021-34770^[1] (CVSS score: 10.0) –
  Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers
  CAPWAP Remote Code Execution Vulnerability
• CVE-2021-34727^[2] (CVSS score: 9.8) –
  Cisco IOS XE SD-WAN Software Buffer Overflow Vulnerability
• CVE-2021-1619^[3] (CVSS score: 9.8) –
  Cisco IOS XE Software NETCONF and RESTCONF Authentication Bypass
  Vulnerability

The most severe of the issues is CVE-2021-34770, which Cisco
calls a “logic error” that occurs during the processing of CAPWAP^[4] (Control And
Provisioning of Wireless Access Points) packets that enable a
central wireless Controller to manage a group of wireless access
points.

“An attacker could exploit this vulnerability by sending a
crafted CAPWAP packet to an affected device,” the company noted in
its advisory. “A successful exploit could allow the attacker to
execute arbitrary code with administrative privileges or cause the
affected device to crash and reload, resulting in a DoS
condition.”

CVE-2021-34727, on the other hand, concerns an insufficient
bounds check when accepting incoming network traffic to the device,
thus allowing an attacker to transmit specially-crafted traffic
that could result in the execution of arbitrary code with
root-level privileges or cause the device to reload. 1000 Series
Integrated Services Routers (ISRs), 4000 Series ISRs, ASR 1000
Series Aggregation Services Routers, and Cloud Services Router
1000V Series that have the SD-WAN feature enabled are impacted by
the flaw.

Lastly, CVE-2021-1619 relates to an “uninitialized variable” in
the authentication, authorization, and accounting (AAA) function of
Cisco IOS XE Software that could permit an authenticated, remote
adversary to “install, manipulate, or delete the configuration of a
network device or to corrupt memory on the device, resulting a
DoS.”

Also addressed by Cisco^[5]
are 15 high-severity vulnerabilities and 15 medium-severity flaws
affecting different components of the IOS XE software as well as
Cisco Access Points platform and Cisco SD-WAN vManage Software.
Users and administrators are recommended to apply the necessary
updates to mitigate any potential exploitation risk by malicious
actors.