Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
n/a — n/a
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.
6.1
1.8%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Published
- Jun 23, 2025
- Modified
- Apr 21, 2026
- Added to KEV
- Apr 20, 2026
- Federal patch due
- Apr 23, 2026
CISA required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Weakness classification
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2025-48700, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2025-48700 were found at last check. Absence here is not proof no exploit exists - see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2025-48700?
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.
How severe is CVE-2025-48700?
CVE-2025-48700 has a CVSS base score of 6.1 out of 10 (CVSS 3.1).
Is CVE-2025-48700 actively exploited in the wild?
Yes. CVE-2025-48700 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Apr 20, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2025-48700?
1.8% - meaning FIRST.org's EPSS model estimates a 1.8% probability this vulnerability will be exploited in the wild within 30 days (76% percentile among all scored CVEs).
What type of vulnerability is CVE-2025-48700?
CVE-2025-48700 is classified under CWE-79 (CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')).
Cross-checked against
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