What is CVE-2026-5268?

CVE-2026-5268 is a critical-severity vulnerability in Ciena 6500 S-series, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.1/10. Published 2026-07-06.

How severe is CVE-2026-5268?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Ciena 6500 S-series

CVE-2026-5268

An authentication bypass vulnerability exists in the default SFTP server component utilized across the Ciena products listed. This vulnerability allows a remote, unauthenticated attacker to bypass security controls and gain unauthorized ac…

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Ciena 6500 S-series — versions R16.96 and prior
Ciena 6500 T-series — versions R16.1 and prior
Ciena Cpl — versions R12.63 and prior
Ciena Pts — versions R16.1 and prior

Weakness classification (CWE)

CWE-288 — Authentication Bypass Using an Alternate Path or Channel

References

7bd90cf1-1651-495e-9ae8-9415fb3c9feb (vendor-advisory)

Frequently asked questions

What is CVE-2026-5268?: CVE-2026-5268 is a critical-severity vulnerability in Ciena 6500 S-series, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.1/10. Published 2026-07-06.
How severe is CVE-2026-5268?: Critical severity. CVSS v3 base score is 9.1 out of 10.