What is CVE-2018-12242?

CVE-2018-12242 is a critical-severity vulnerability in Symantec Messaging Gateway, classified under Improper Authentication. CVSS score: 9.8/10. Published 2018-09-19.

How severe is CVE-2018-12242?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Symantec Messaging Gateway

CVE-2018-12242

The Symantec Messaging Gateway product prior to 10.6.6 may be susceptible to an authentication bypass exploit, which is a type of issue that can allow attackers to potentially circumvent security mechanisms currently in place and gain access to the system or network.

Vulnerability class: Broken Authentication

Published 2018-09-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.030 (86.6th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 87th percentile — 86.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.030 · newest: 0.030 · change: 0.000

Affected products

Symantec Messaging Gateway
Symantec Corporation Messaging Gateway — versions Prior to 10.6.6

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

support.symantec.com/en_US/article.SYMSA1461.html (Vendor Advisory)
www.securityfocus.com/bid/105329 (VDB Entry, Third Party Advisory, vdb-entry)

Frequently asked questions

What is CVE-2018-12242?: CVE-2018-12242 is a critical-severity vulnerability in Symantec Messaging Gateway, classified under Improper Authentication. CVSS score: 9.8/10. Published 2018-09-19.
How severe is CVE-2018-12242?: Critical severity. CVSS v3 base score is 9.8 out of 10.