Cisco IOS XE Software DNS NAT Protocol Application Layer Gateway DoS (cisco-sa-alg-dos-hbBS7SZE)

high Nessus Plugin ID 152176
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The remote device is missing a vendor-supplied security patch


According to its self-reported version, Cisco IOS-XE Software is affected by a denial of service vulnerability in the DNS Application Layer Gateway (ALG) functionality used by Network Address Translation (NAT). The vulnerability is due to a logic error that occurs when an affected device inspects certain DNS packets. An unauthenticated, remote attacker can exploit this, by sending crafted DNS packets through an affected device that is performing NAT for DNS packets, to cause the device to reload.

Please see the included Cisco BID and Cisco Security Advisory for more information.


Upgrade to the relevant fixed version referenced in Cisco bug ID CSCvv65113

See Also

Plugin Details

Severity: High

ID: 152176

File Name: cisco-sa-alg-dos-hbBS7SZE-iosxe.nasl

Version: 1.5

Type: combined

Family: CISCO

Published: 8/2/2021

Updated: 8/3/2021

Dependencies: cisco_ios_xe_version.nasl

Risk Information

CVSS Score Source: CVE-2021-1446


Risk Factor: Low

Score: 3.6


Risk Factor: High

Base Score: 7.1

Temporal Score: 5.3

Vector: AV:N/AC:M/Au:N/C:N/I:N/A:C

Temporal Vector: E:U/RL:OF/RC:C


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:cisco:ios_xe

Required KB Items: Host/Cisco/IOS-XE/Version

Exploit Ease: No known exploits are available

Patch Publication Date: 3/24/2021

Vulnerability Publication Date: 3/24/2021

Reference Information

CVE: CVE-2021-1446


CISCO-SA: cisco-sa-alg-dos-hbBS7SZE

CWE: 754