---
id: CVE-2021-1619
title: Cisco IOS XE Software NETCONF/RESTCONF AAA Vulnerability
summary: "A vulnerability in the authentication, authorization, and accounting (AAA) function of Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass NETCONF or RESTCONF authentication and do either of the following:\r\n\r\nIn…"
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: vendor
vendor: Cisco
product: Cisco IOS XE Software
affected:
  - ios_xe_software 16.3.1
  - ios_xe_software 16.4.1
  - ios_xe_software 16.3.2
  - ios_xe_software 16.3.3
  - ios_xe_software 16.4.2
  - ios_xe_software 16.5.1
  - ios_xe_software 16.6.1
  - ios_xe_software 16.7.1
  - ios_xe_software 16.8.1
  - ios_xe_software 16.3.1a
  - ios_xe_software 16.3.4
  - ios_xe_software 16.5.1a
  - ios_xe_software 16.9.1
  - ios_xe_software 16.10.1
  - ios_xe_software 16.5.1b
  - ios_xe_software 16.11.1
  - ios_xe_software 16.12.1
  - ios_xe_software 16.6.2
  - ios_xe_software 16.3.5
  - ios_xe_software 16.5.2
  - ios_xe_software 16.3.5b
  - ios_xe_software 16.7.1a
  - ios_xe_software 16.4.3
  - ios_xe_software 16.3.6
  - ios_xe_software 16.6.3
  - ios_xe_software 16.9.2
  - ios_xe_software 16.5.3
  - ios_xe_software 16.7.1b
  - ios_xe_software 16.6.4
  - ios_xe_software 16.8.1a
  - ios_xe_software 16.8.1b
  - ios_xe_software 16.8.1s
  - ios_xe_software 16.7.2
  - ios_xe_software 16.8.1c
  - ios_xe_software 16.3.7
  - ios_xe_software 16.6.5
  - ios_xe_software 16.9.1a
  - ios_xe_software 16.8.1d
  - ios_xe_software 16.9.1b
  - ios_xe_software 16.7.3
published: '2021-09-22'
updated: '2021-09-22'
sourceUpdated: '2021-09-22T16:00:00+00:00'
source: CSAF
sourceUrl: >-
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aaa-Yx47ZT8Q
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aaa-Yx47ZT8Q
  - url: 'https://software.cisco.com'
tags:
  - csaf
  - vendor-advisory
  - cisco
epss: 0.01758
epssPercentile: 0.76973
ingestedAt: '2026-09-25T07:41:37.793Z'
---

## Overview

A vulnerability in the authentication, authorization, and accounting (AAA) function of Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass NETCONF or RESTCONF authentication and do either of the following:

Install, manipulate, or delete the configuration of an affected device
Cause memory corruption that results in a denial of service (DoS) on an affected device

This vulnerability is due to an uninitialized variable. An attacker could exploit this vulnerability by sending a series of NETCONF or RESTCONF requests to an affected device. A successful exploit could allow the attacker to use NETCONF or RESTCONF to install, manipulate, or delete the configuration of a network device or to corrupt memory on the device, resulting a DoS.

Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.



This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication. ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74581"]

## Vendor advisories

- **cisco-sa-aaa-Yx47ZT8Q** · Cisco · affected: Cisco IOS XE Software (120 versions), Cisco 1000 Series Integrated Services Routers, Cisco ASR 1000 Series Aggregation Services Routers, Cisco 4000 Series Integrated Services Routers, Cisco Integrated Services Virtual Router, Cisco Cloud Services Router 1000V Series, … · updated 2021-09-22 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aaa-Yx47ZT8Q)

**Cisco IOS XE Software NETCONF and RESTCONF Authentication Bypass Vulnerability**. Released 2021-09-22.

Affected:

- Cisco IOS XE Software 16.3.1
- Cisco IOS XE Software 16.4.1
- Cisco IOS XE Software 16.3.2
- Cisco IOS XE Software 16.3.3
- Cisco IOS XE Software 16.4.2
- Cisco IOS XE Software 16.5.1
- Cisco IOS XE Software 16.6.1
- Cisco IOS XE Software 16.7.1
- Cisco IOS XE Software 16.8.1
- Cisco IOS XE Software 16.3.1a
- Cisco IOS XE Software 16.3.4
- Cisco IOS XE Software 16.5.1a
- Cisco IOS XE Software 16.9.1
- Cisco IOS XE Software 16.10.1
- Cisco IOS XE Software 16.5.1b
- Cisco IOS XE Software 16.11.1
- Cisco IOS XE Software 16.12.1
- Cisco IOS XE Software 16.6.2
- Cisco IOS XE Software 16.3.5
- Cisco IOS XE Software 16.5.2
- Cisco IOS XE Software 16.3.5b
- Cisco IOS XE Software 16.7.1a
- Cisco IOS XE Software 16.4.3
- Cisco IOS XE Software 16.3.6
- Cisco IOS XE Software 16.6.3
- Cisco IOS XE Software 16.9.2
- Cisco IOS XE Software 16.5.3
- Cisco IOS XE Software 16.7.1b
- Cisco IOS XE Software 16.6.4
- Cisco IOS XE Software 16.8.1a
- Cisco IOS XE Software 16.8.1b
- Cisco IOS XE Software 16.8.1s
- Cisco IOS XE Software 16.7.2
- Cisco IOS XE Software 16.8.1c
- Cisco IOS XE Software 16.3.7
- Cisco IOS XE Software 16.6.5
- Cisco IOS XE Software 16.9.1a
- Cisco IOS XE Software 16.8.1d
- Cisco IOS XE Software 16.9.1b
- Cisco IOS XE Software 16.7.3

## Remediation

Cisco has released software updates that address this vulnerability. https://software.cisco.com