Critical Cryptography

CVE-2026-20184 — Cisco Webex SSO with Control Hub - Improper Certificate Validation Enables User Impersonation

A vulnerability in the integration of single sign-on (SSO) with Control Hub in Cisco Webex Services could have allowed an unauthenticated, remote attacker to impersonate any user within the service. This vulnerability existed because of improper certificate validation. Prior to this vulnerability being addressed, an attacker could have exploited this vulnerability by connecting to a service endpoint and supplying a crafted token. A successful exploit could have allowed the attacker to gain unauthorized access to legitimate Cisco Webex services.

Published Apr 15, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.5% (30-day exploitation probability)+6
Technical severity (critical)+10
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.52%

ahead of 43% of scored CVEs · Oct 14, 2026

Affects

Cisco

Webex Meetings

CVSS base

9.8

Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Webex Meetings).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Webex Meetings	version 44.3version 43.4.1version 43.4.2version 43.5.0version 43.6.0version 43.6.1version 43.7version 43.8 and 48 more version 43.9version 43.10version 43.11version 43.12version 44.1version 44.2version 43.4version 44.4version 44.5version 44.6version 44.7version 44.8version 44.9version 44.10version 44.11version 44.12version 45.1version 45.2version 45.3version 45.4version 39.8version 39.9version 40.4.10version 39.6version 40.6.2version 39.8.2version 39.8.4version 40.1version 39.11version 39.7.4version 39.9.1version 40.4version 40.6version 39.7version 39.7.7version 39.8.3version 40.2version 39.10version 42.6version 42.7version 42.8version 42.9version 42.10version 42.11version 42.12version 43.1version 43.2version 43.3	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.8	CVSS 3.1	Critical	3.9	5.9	psirt@cisco.com via NIST National Vulnerability Database
9.8	CVSS 3.1	Critical	—	—	cisco via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-295 · Improper Certificate Validation

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.52%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Check TLS negotiations and unexpected certificates in the component’s traffic.

web/proxy/WAF logsnetwork IDS/IPS

Analysis and videos

CVE-2026-20184: Cisco Webex SSO with Control Hub - Improper Certificate Validation Enables User Impersonation
CVE-2026-20184 affects the single sign-on integration between Cisco Webex Services and Control Hub. The flaw stems from improper certificate validation and, according to the record, could let an unauthenticated remote attacker impersonate any user in the service. The record reports a CVSS 3.1 base score of 9.8 (critical) and no KEV listing, but it lists no affected or fixed versions.

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cisco/cisco webex meetings
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 9.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Awaiting Analysis
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Apr 15, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-cui-cert
NIST National Vulnerability Database

Elsewhere on this site

Cisco
every CVE for this vendor

Cryptography
same class

CWE-295
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-20233 Cisco Webex Meetings Cross-Site Scripting Vulnerability Jun 3, 2026
Medium CVE-2026-20219 Authorization Bypass Through User-Controlled Key (IDOR) in Cisco Webex Meetings May 6, 2026
Medium CVE-2026-20149 Cross-site Scripting (XSS) in Cisco Webex Mar 4, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20184 is "Cisco Webex SSO with Control Hub - Improper Certificate Validation Enables User Impersonation", rated Critical. It affects Webex Meetings (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.52% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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