What is CVE-2026-21718?

CVE-2026-21718 is a critical-severity vulnerability in Copeland Xweb 300d Pro, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 10.0/10. Published 2026-02-27.

How severe is CVE-2026-21718?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Vulnerability in Copeland Xweb 300d Pro

CVE-2026-21718

An authentication bypass vulnerability exists in Copeland XWEB Pro version 1.12.1 and prior, enabling any attackers to bypass the authentication requirement and achieve pre-authenticated code execution on the system.

Vulnerability class: POODLE (CVE-2014-3566)

Published 2026-02-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (37.4th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000

Affected products

Weakness classification (CWE)

CWE-327 — Use of a Broken or Risky Cryptographic Algorithm

References

webapps.copeland.com/Dixell/Pages/SystemSoftwareUpdate (Product)
www.cisa.gov/news-events/ics-advisories/icsa-26-057-10 (US Government Resource, Third Party Advisory)
github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-057-10.js… (Third Party Advisory)

Frequently asked questions

What is CVE-2026-21718?: CVE-2026-21718 is a critical-severity vulnerability in Copeland Xweb 300d Pro, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 10.0/10. Published 2026-02-27.
How severe is CVE-2026-21718?: Critical severity. CVSS v3 base score is 10.0 out of 10.