An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1.
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-79.
Summary
An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Zimbra Briefcase feature due to insufficient sanitization of specific uploaded file types. When a user opens a publicly shared Briefcase file containing malicious scripts, the embedded JavaScript executes in the context of the user's session. This allows an attacker to run arbitrary scripts, potentially leading to data exfiltration or other unauthorized actions on behalf of the victim user.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-33370
- 2026-10-03 Alias added: GHSA-cwch-jfrm-2v7r
References
More Synacor Zimbra Collaboration Suite vulnerabilities
- TI-2024-30554 The postjournal service in Zimbra Collaboration (ZCS) before 8.8.15 Patch 46, 9 before… KEVCVSS 3.1CRITICAL 10.0
- TI-2022-19841 An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0. KEVCVSS 3.1CRITICAL 9.8
- TI-2022-17239 Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 has mboximport functionality that… KEVCVSS 3.1CRITICAL 9.8
- TI-2022-10792 Zimbra Collaboration (aka ZCS) 8.8.15 and 9.0 allows an unauthenticated attacker to… KEVCVSS 3.1CRITICAL 9.8
- TI-2020-06312 Zimbra Collaboration Suite (ZCS) before 8.8.15 Patch 7 allows SSRF when WebEx zimlet is… KEVCVSS 3.1CRITICAL 9.8
- TI-2019-07076 mailboxd component in Synacor Zimbra Collaboration Suite 8.7.x before 8.7.11p10 has an… KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-33370 · CVE Program
- CVE-2026-33370 · NVD
- FIRST EPSS
- GHSA-cwch-jfrm-2v7r · GitHub Advisory Database · CC BY 4.0
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