Description
An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.
Published: 2025-06-23
Score: 6.1 Medium
EPSS: 18.8% Moderate
KEV: Yes
Impact: Cross‑Site Scripting
Action: Immediate Patch
AI Analysis

Impact

A Cross‑Site Scripting vulnerability exists in the Zimbra Classic UI, allowing an attacker to execute arbitrary JavaScript when a user views a crafted e‑mail message. The flaw stems from insufficient sanitization of HTML content, especially tag structures that include an @import directive or other script injection vectors. The resulting arbitrary code execution can lead to unauthorized access to sensitive information within the user's session. The vulnerability requires no additional user interaction beyond opening the mail.

Affected Systems

The flaw affects Zimbra Collaboration Suite 8.8.15, 9.0.0, 10.0, and 10.1, all deployed by Synacor. The CPE list enumerates many patch releases for 8.8.15 and 9.0.0, while the description references 10.0 and 10.1.

Risk and Exploitability

The CVSS score of 6.1 indicates a moderate severity vulnerability, while an EPSS score of 20% indicates a lower probability that this vulnerability will be exploited in the wild. The vulnerability is listed in the CISA KEV catalog, underscoring its real‑world impact. Attackers can exploit it by sending a specially crafted email that a user opens in the Classic UI, with no further credentials or actions required.

Generated by OpenCVE AI on April 28, 2026 at 11:11 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the latest vendor patch for Zimbra Collaboration Suite 8.8.15 or 9.0.0 that removes the vulnerable code.
  • Configure the mail system to strip or block @import directives and script attributes from email bodies before they reach the Classic UI.
  • Temporarily disable the Classic UI for all untrusted user accounts until the patch is in place.

Generated by OpenCVE AI on April 28, 2026 at 11:11 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
EUVD EUVD EUVD-2025-18891 An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.
History

Tue, 28 Apr 2026 01:45:00 +0000

Type Values Removed Values Added
Title Cross‑Site Scripting via Crafted Emails in Zimbra Classic UI

Wed, 22 Apr 2026 12:30:00 +0000

Type Values Removed Values Added
Title Cross‑Site Scripting via Crafted Emails in Zimbra Classic UI

Mon, 20 Apr 2026 20:15:00 +0000

Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'active', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 20 Apr 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics kev

{'dateAdded': '2026-04-20T00:00:00+00:00', 'dueDate': '2026-04-23T00:00:00+00:00'}

Sat, 12 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00031}

 epss

{'score': 0.00032}

Fri, 11 Jul 2025 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Synacor
Synacor zimbra Collaboration Suite
CPEs cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:-:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p10:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p11:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p12:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p13:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p14:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p15:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p16:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p17:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p18:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p19:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p20:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p21:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p22:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p23:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p24:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p25:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p26:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p27:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p28:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p29:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p2:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p30:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p31.1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p31:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p32:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p33:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p34:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p35:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p36:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p37:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p38:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p39:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p3:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p40:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p41:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p42:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p43:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p44:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p45:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p46:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p4:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p5:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p6:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p7:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p8:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p9:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:-:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p10:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p11:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p12:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p13:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p14:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p15:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p16:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p17:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p18:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p19:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p20:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p21:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p22:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p23:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24.1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p25:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p26:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p27:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p28:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p29:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p2:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p30:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p31:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p32:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p33:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p34:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p35:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p36:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p37:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p38:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p39:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p3:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p40:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p41:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p42:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p4:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p5:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p6:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p7:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p8:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p9:*:*:*:*:*:*
Vendors & Products Synacor
Synacor zimbra Collaboration Suite

Tue, 24 Jun 2025 16:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-79
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 23 Jun 2025 14:45:00 +0000

Type Values Removed Values Added
Description An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.
References

Subscriptions

Synacor Zimbra Collaboration Suite
Zimbra Zimbra
cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-04-21T03:55:38.511Z

Reserved: 2025-05-23T00:00:00.000Z

Link: CVE-2025-48700

cve-icon Vulnrichment

Updated: 2025-06-24T13:48:29.651Z

cve-icon NVD

Status : Analyzed

Published: 2025-06-23T15:15:27.930

Modified: 2026-04-21T12:48:23.763

Link: CVE-2025-48700

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-28T11:15:26Z

Weaknesses