CVE-2021-1221Network attack vector

Recipient redirection via unvalidated invitation URL

Published Feb 4, 2021 · Updated Nov 8, 2024

Hyperlink injection in Cisco WebEx Meetings Server allows remote authenticated users to place arbitrary links in meeting invitation emails. The meeting user interface accepts a user-supplied URL without sufficient validation and inserts it into an invitation sent from a trusted source. Exploitation requires meeting privileges and a recipient to click the injected link, enabling redirection to an attacker-chosen destination.

CVSS severity4.1
Medium
EPSS probability1.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hyperlink injection in Cisco WebEx Meetings Server allows remote authenticated users to place arbitrary links in meeting invitation emails. The meeting user interface accepts a user-supplied URL without sufficient validation and inserts it into an invitation sent from a trusted source. Exploitation requires meeting privileges and a recipient to click the injected link, enabling redirection to an attacker-chosen destination.

The record

CVE
CVE-2021-1221
Published
Feb 4, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco WebEx Meetings Server
Classifications
CWE-20, CWE-74, T1566.002, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 4, 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 privilegesauthenticated

What is affected?

ClamAV · Cisco WebEx Meetings Serverversion=n/a

Published CVSS scores

4.1Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
3.5NIST NVDAV:N/AC:M/Au:S/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1566.002Spearphishing Link
T1204.001Malicious 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

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Your stack

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