What is CVE-2018-18631?

CVE-2018-18631 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2019-05-29.

How severe is CVE-2018-18631?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Synacor Zimbra Collaboration Suite

CVE-2018-18631

mailboxd component in Synacor Zimbra Collaboration Suite 8.6, 8.7 before 8.7.11 Patch 7, and 8.8 before 8.8.10 Patch 2 has Persistent XSS.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2019-05-29 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (61.0th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 61.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Synacor Zimbra Collaboration Suite — versions 8.6.0, 8.7.11, 8.8.9

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

wiki.zimbra.com/wiki/Zimbra_Security_Advisories (Vendor Advisory)
bugzilla.zimbra.com/show_bug.cgi (Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2018-18631?: CVE-2018-18631 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2019-05-29.
How severe is CVE-2018-18631?: Medium severity. CVSS v3 base score is 6.1 out of 10.