CVE-2021-1460Network attack vector

Remote service interruption via crafted TCP flood

Published Mar 24, 2021 · Updated Nov 8, 2024

Denial of service in Cisco IOS before 15.9(3)M3 allows remote attackers to interrupt IOx application management via crafted TCP traffic. The IOx web server handles a high and sustained rate of crafted TCP packets without sufficient error handling and stops processing requests. The device must be a Cisco 809 or 829 Industrial ISR with the IOx application hosting environment running; the failure interrupts application management without affecting confidentiality or integrity.

CVSS severity5.3
Medium
EPSS probability1.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco IOS before 15.9(3)M3 allows remote attackers to interrupt IOx application management via crafted TCP traffic. The IOx web server handles a high and sustained rate of crafted TCP packets without sufficient error handling and stops processing requests. The device must be a Cisco 809 or 829 Industrial ISR with the IOx application hosting environment running; the failure interrupts application management without affecting confidentiality or integrity.

The record

CVE
CVE-2021-1460
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-400, T1498.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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 IOSversion=n/a

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-400Uncontrolled Resource Consumption
T1498.003Application Exhaustion Flood

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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