CVE-2026-93647 — CRITICAL (9.3)

Vulnerability Description

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.

CVSS Score

9.3

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

NONE

Related Weaknesses (CWE)

CWE-79

References

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories

FAQ

What is CVE-2026-93647?

CVE-2026-93647 is a vulnerability with a CVSS score of 9.3 (CRITICAL). 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...

How severe is CVE-2026-93647?

CVE-2026-93647 has been rated CRITICAL with a CVSS base score of 9.3/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-93647?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.