Critical

Improper Certificate Validation in Cisco Webex SSO with Control Hub

IdentifiersCVE-2026-20184CWE-295· Improper Certificate Validation

CVE-2026-20184 is a critical vulnerability in the integration of single sign-on (SSO) with Control Hub in Cisco Webex Services. The flaw is caused by improper certificate validation in the Webex SSO authentication flow. According to the provided content, an unauthenticated remote attacker could exploit the issue by connecting to a Webex service endpoint and supplying a crafted authentication token. Because certificate validation was not performed correctly, the service could accept a forged or manipulated token as legitimate, enabling the attacker to impersonate any user within the service and access Webex resources as that user.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation could allow complete impersonation of any user in the affected Webex environment and unauthorized access to legitimate Cisco Webex services. Because SSO in Control Hub governs access across the broader Webex ecosystem, the impact can extend to the services and data available to the impersonated account, with high impact to confidentiality, integrity, and availability as reflected by the provided CVSS vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Mitigation

If you can’t patch tonight, do this now.

The provided content states that no temporary workaround is available. As an interim risk-reduction measure pending full remediation, organizations should review and validate SSO certificate configuration in Control Hub, closely monitor authentication activity for anomalous logins or user impersonation indicators, and prioritize completion of the certificate update process described by Cisco. However, the primary mitigation is to implement Cisco’s prescribed certificate and configuration updates.

Remediation

Patch, then assume compromise.

Cisco addressed the vulnerability in its cloud-based Webex Services. The provided content indicates that customers using SSO integration should follow Cisco’s advisory and upload a new SAML certificate for their Identity Provider in Webex Control Hub to fully remediate exposure. Administrators were advised to consult Cisco Security Advisory cisco-sa-webex-cui-cert-8jSZYhWL for exact remediation steps, renew the relevant Service Provider certificate as directed, download updated metadata, upload it to the Identity Provider management interface, and validate the change using the documented SSO testing workflow.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Cisco SystemsWebexapplication

Cisco SystemsWebex Servicesapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

26 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

26 SOURCESView more in app

thecyberexpress com vulnerabilitiesNews

Apr 20, 2026

Cisco ISE Vulnerabilities Enable Remote Code Execution

A critical Cisco Webex Services vulnerability in SSO integration with Control Hub caused by improper certificate validation, allowing an unauthenticated remote attacker to impersonate any user.

security affairsNews

Apr 16, 2026

Cisco fixed four critical flaws in Identity Services and Webex

An improper certificate validation vulnerability in Webex SSO integration with Control Hub that could allow unauthenticated user impersonation and unauthorized access to Webex services.

scworldNews

Apr 16, 2026

Cisco patches critical bugs in Webex, ISE | news | SC Media

A critical Cisco Webex vulnerability affecting SSO integration with Control Hub that could allow a remote attacker to impersonate any user by exploiting flawed certificate validation and forging an authentication token.

the hacker newsNews

Apr 16, 2026

Cisco Patches Four Critical Identity Services, Webex Flaws Enabling Code Execution

An improper certificate validation flaw in Cisco Webex Services SSO integration with Control Hub that could let an unauthenticated remote attacker impersonate any user and gain unauthorized access.

+3 more in the timeline

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity18