CVE-2021-1619Network attack vector

Unauthenticated configuration changes and crash via uninitialized variable

Published Sep 23, 2021 · Updated Nov 7, 2024

Authentication bypass in Cisco IOS XE Software allows remote attackers to alter device configuration or crash affected devices. The AAA function reads an uninitialized variable while processing a series of NETCONF or RESTCONF requests, bypassing authentication and permitting memory corruption. Exposure requires AAA, NETCONF or RESTCONF, and an enable password without an enable secret; successful requests can install, modify, or delete configuration or interrupt service through a crash.

CVSS severity9.8
Critical
EPSS probability1.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Cisco IOS XE Software allows remote attackers to alter device configuration or crash affected devices. The AAA function reads an uninitialized variable while processing a series of NETCONF or RESTCONF requests, bypassing authentication and permitting memory corruption. Exposure requires AAA, NETCONF or RESTCONF, and an enable password without an enable secret; successful requests can install, modify, or delete configuration or interrupt service through a crash.

The record

CVE
CVE-2021-1619
Published
Sep 23, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-908, CWE-824, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XE Softwareversion=n/a

Published CVSS scores

9.8Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
9.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
CWE-824Access of Uninitialized Pointer
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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