CVE-2021-1420Network attack vector

Client-side content modification via unchecked HTML parameters

Published Apr 8, 2021 · Updated Nov 8, 2024

HTML injection in certain Cisco Webex Meetings web pages allows remote attackers to alter page content through a crafted link. Affected pages inadequately validate parameter values and insert attacker-supplied HTML into the page rendered in a user's browser. Exploitation requires user interaction with the link and permits redirection to malicious sites or further client-side attacks.

CVSS severity4.7
Medium
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

HTML injection in certain Cisco Webex Meetings web pages allows remote attackers to alter page content through a crafted link. Affected pages inadequately validate parameter values and insert attacker-supplied HTML into the page rendered in a user's browser. Exploitation requires user interaction with the link and permits redirection to malicious sites or further client-side attacks.

The record

CVE
CVE-2021-1420
Published
Apr 8, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Webex Meetings
Classifications
CWE-80, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 · Webex Meetingsversion=n/a

Published CVSS scores

4.7Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:P/A:N

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-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo