What is CVE-2026-93647?

CVE-2026-93647 is a critical-severity vulnerability, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2026-09-25.

How severe is CVE-2026-93647?

Critical severity. CVSS v3 base score is 9.3 out of 10.

CVE-2026-93647

CVE-2026-93647

An unauthenticated calendar sender can place active markup in a COUNTER message's RFC From address. Selecting the message in Zimbra Classic triggers stored XSS, allowing the attacker to access mailbox data and act as the victim.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-09-25 · last modified 2026-09-26.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

wiki.zimbra.com/wiki/Zimbra_Security_Advisories (vendor-advisory)

Frequently asked questions

What is CVE-2026-93647?: CVE-2026-93647 is a critical-severity vulnerability, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2026-09-25.
How severe is CVE-2026-93647?: Critical severity. CVSS v3 base score is 9.3 out of 10.