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Critical 9.3Published Sep 25, 2026
CVE-2026-93647Zimbra Collaboration Suite Classic Web Client Stored Cross-Site Scripting via Crafted Calendar COUNTER Message From Address
Updated under an hour ago ()
Does this affect you?
It affects Zimbra Collaboration Suite (ZCS). Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 9.3 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
- Weakness (CWE)
- CWE-79
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- rapid7
- NVD analysis
- Awaiting Analysis
- Record last updated
- Sep 28, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Zimbra Zimbra Collaboration Suite (ZCS) zimbra:collaboration_suite_zcs (from the name) | before 10.1.21 | CNA record |
References
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisoriesvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.