CVE · Cisco Webex · cloud-relevant

CVE-2026-20184: Cisco Webex SSO token validation bypass

Improper certificate validation in Cisco Webex SSO integration. An unauthenticated remote attacker could supply a crafted token to the SSO endpoint and impersonate a legitimate Webex user.

01 Vulnerability summary
n/a
CVSS v3 base
HIGH
Severity
Apr 2026
Published (NVD)
None known
Exploit status

Per the NVD entry, an attacker could exploit this vulnerability by connecting to a Cisco Webex service endpoint and supplying a crafted token. A successful exploit allowed the attacker to gain unauthorised access to legitimate Cisco Webex services and impersonate any user within the service. The advisory is recorded as 'cisco-sa-webex-cui-cert-8jSZYhWL' in Cisco's Security Center; it is fixed in current Webex builds.

Affected products

02 Mapped MITRE ATT&CK techniques

Detection coverage for this CVE follows the techniques an attacker would exercise. The actionable Sigma rules + DCV coverage data live on the linked technique pages.

CVE-specific Sigma rule generation is under integrity review. See our integrity contract for what we publish today and what graduates next.

Sources
  • NVD, https://nvd.nist.gov/vuln/detail/CVE-2026-20184
  • Cisco Security Center advisory, https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-cui-cert-8jSZYhWL
  • MITRE ATT&CK T1190 Exploit Public-Facing Application, https://attack.mitre.org/techniques/T1190/
Last verified: 2026-04-24