CVE-2021-1403Network attack vector

Device reload via cross-site WebSocket hijacking

Published Mar 24, 2021 · Updated Nov 8, 2024

Cross-site WebSocket hijacking in Cisco IOS XE Software web UI allows remote attackers to force an affected device to reload. The enabled web UI accepts attacker-driven WebSocket traffic from a crafted page without sufficient HTTP authenticity protections. An authenticated web UI user must follow the link; successful memory corruption reloads the device and interrupts network service.

CVSS severity7.4
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site WebSocket hijacking in Cisco IOS XE Software web UI allows remote attackers to force an affected device to reload. The enabled web UI accepts attacker-driven WebSocket traffic from a crafted page without sufficient HTTP authenticity protections. An authenticated web UI user must follow the link; successful memory corruption reloads the device and interrupts network service.

The record

CVE
CVE-2021-1403
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-345, T1499.004, T1204.001
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 IOS XE Softwareversion=n/a

Published CVSS scores

7.4CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1499.004Endpoint Denial of Service: Application or System Exploitation
T1204.001User Execution: Malicious Link

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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