- Critical 9.3
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.
Scores
The facts
- Published
- 25 September 2026
- Last changed
- 29 September 2026
- NVD status
- Awaiting Analysis
- Severity
- Critical, CVSS 9.3 out of 10 (version 3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N - Weakness
- Known exploited
- Not in the CISA Known Exploited Vulnerabilities catalogue in this build.
- EPSS
- 0.2% chance of exploitation activity in the next 30 days (percentile 13).
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