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CVE-2026-20178 Cisco CVE debrief

A vulnerability in the browser-based version of Cisco Webex App could have allowed an unauthenticated, remote attacker to redirect users to a malicious webpage. Cisco has addressed this vulnerability in the Cisco Webex App, and no customer action is needed. This vulnerability existed due to improper input validation of URL parameters in an HTTP request. Prior to this vulnerability being addressed, an attacker could have exploited this vulnerability by persuading a user to click a crafted URL. A successful exploit could have allowed the attacker to redirect a user to a malicious website. The vulnerability has been addressed, and users should ensure they are using the updated version of the application.

Vendor
Cisco
Product
Cisco Webex App
CVSS
MEDIUM 4.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-17
Original CVE updated
2026-06-22
Advisory published
2026-06-17
Advisory updated
2026-06-22

Who should care

Users of Cisco Webex App should be aware of this vulnerability and ensure they are using the updated version of the application. This vulnerability could have allowed an unauthenticated, remote attacker to redirect users to a malicious webpage. Cisco has addressed this vulnerability, but users should still verify their application version.

Technical summary

The vulnerability existed due to improper input validation of URL parameters in an HTTP request. An attacker could have exploited this vulnerability by persuading a user to click a crafted URL, potentially redirecting the user to a malicious website. Cisco has addressed this vulnerability in the Cisco Webex App, and no customer action is needed. The vulnerability was publicly disclosed and addressed promptly.

Defensive priority

Medium priority due to the CVSS score of 4.3 and the potential for redirecting users to malicious websites.

Recommended defensive actions

  • Ensure the Cisco Webex App is updated to the latest version.
  • Educate users on the potential risks of clicking on unknown URLs.
  • Monitor for any suspicious activity related to the Cisco Webex App.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record was published on 2026-06-17T18:17:35.587Z and was last modified on 2026-06-22T14:17:11.023Z. The NVD entry is currently Analyzed. Cisco has addressed this vulnerability in the Cisco Webex App, and no customer action is needed. The vulnerability existed due to improper input validation of URL parameters in an HTTP request. An attacker could have exploited this vulnerability by persuading a user to click a crafted URL, potentially redirecting the user to a malicious website. Evidence is limited to CVE and NVD details.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-20178 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-20178

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-20178 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-20178

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.