How severe is CVE-2021-40128?

CVE-2021-40128 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-40128 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40128?

CVE-2021-40128 affects Cisco Webex Meetings. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40128?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-40128 published?

CVE-2021-40128 was published on 2021-11-04 and last updated on 2026-06-17.

CVE-2021-40128

CVE-2021-40128 is a medium-severity vulnerability in Cisco Webex Meetings with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-183.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-183
Affected product: Cisco Webex Meetings
Published: 2021-11-04
Last modified: 2026-06-17

Description

A vulnerability in the account activation feature of Cisco Webex Meetings could allow an unauthenticated, remote attacker to send an account activation email with an activation link that points to an arbitrary domain. This vulnerability is due to insufficient validation of user-supplied parameters. An attacker could exploit this vulnerability by sending a crafted HTTP request to the account activation page of Cisco Webex Meetings. A successful exploit could allow the attacker to send to any recipient an account activation email that contains a tampered activation link, which could direct the user to an attacker-controlled website.

Frequently asked questions

What is CVE-2021-40128?: A vulnerability in the account activation feature of Cisco Webex Meetings could allow an unauthenticated, remote attacker to send an account activation email with an activation link that points to an arbitrary domain. This vulnerability is due to insufficient validation of user-supplied parameters. An attacker could exploit this vulnerability by sending a crafted HTTP request to the account activation page of Cisco Webex Meetings. A successful exploit could allow the attacker to send to any recipient an account activation email that contains a tampered activation link, which could direct the user to an attacker-controlled website.
How severe is CVE-2021-40128?: CVE-2021-40128 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-40128 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40128?: CVE-2021-40128 affects Cisco Webex Meetings. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40128?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-40128 published?: CVE-2021-40128 was published on 2021-11-04 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-activation-3sdNFxcy

Affected products (1)

cpe:2.3:a:cisco:webex_meetings:-:*:*:*:*:*:*:*

More vulnerabilities in Cisco Webex Meetings

CVE-2018-0264 — Critical (CVSS 9.6): A vulnerability in the Cisco WebEx Network Recording Player for Advanced Recording Format (ARF) files could allow an…
CVE-2018-0104 — Critical (CVSS 9.6): A vulnerability in Cisco WebEx Network Recording Player for Advanced Recording Format (ARF) files could allow a remote…
CVE-2017-12372 — Critical (CVSS 9.6): A "Cisco WebEx Network Recording Player Remote Code Execution Vulnerability" exists in Cisco WebEx Network Recording…
CVE-2017-12371 — Critical (CVSS 9.6): A "Cisco WebEx Network Recording Player Remote Code Execution Vulnerability" exists in Cisco WebEx Network Recording…
CVE-2017-12370 — Critical (CVSS 9.6): A "Cisco WebEx Network Recording Player Remote Code Execution Vulnerability" exists in Cisco WebEx Network Recording…
CVE-2017-12369 — Critical (CVSS 9.6): A "Cisco WebEx Network Recording Player Out-of-Bounds Vulnerability" exists in Cisco WebEx Network Recording Player for…

All CVEs affecting Cisco Webex Meetings →

Other CWE-183 vulnerabilities

CVE-2026-3490 — Critical (CVSS 10.0): picklescan before 1.0.4 fails to block pkgutil.resolve_name, allowing attackers to bypass the entire blocklist by…
CVE-2026-54316 — Critical (CVSS 9.1): Claude Code is an agentic coding tool. From 0.2.54 until 2.1.163, because the hostname huggingface.co was pre-approved…
CVE-2026-29514 — High (CVSS 8.8): NetBox versions 4.3.5 through 4.5.4 contain a remote code execution vulnerability in the…
CVE-2026-46391 — High (CVSS 8.7): HAX CMS helps manage microsite universe with PHP or NodeJs backends. Starting in version 9.0.1 and prior to version…
CVE-2025-53762 — High (CVSS 8.7): Permissive list of allowed inputs in Microsoft Purview allows an authorized attacker to elevate privileges over a…
CVE-2026-41387 — High (CVSS 7.8): OpenClaw before 2026.3.22 contains an incomplete host environment variable sanitization vulnerability in…

Browse all CWE-183 vulnerabilities →