CVEs / CVE-2025-48700
CVE-2025-48700: Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
- Known exploited in the CISA KEV catalog since 20 Apr 2026
- medium 6.1 CVSS 3.1 (from the CNA)
- EPSS 1.71% chance of exploitation in the next 30 days, higher than 77% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that could allow attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information.
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| n/a n/a | n/a | — |
Exploitation
| In CISA KEV since | 20 Apr 2026 |
|---|---|
| Due date for US federal agencies | 23 Apr 2026 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 6.1 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NScored by the CNA (134c704f-9b21-4f2e-91b3-4a467353bcc0) |
|---|---|
| Weakness | CWE-79 |
References
- CVE-2025-48700 on NVD
- CVE-2025-48700 in the CISA KEV catalog
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories (cited by CISA)
- CVE-2025-48700 on OSV
- https://wiki.zimbra.com/wiki/Security_Center Release Notes
- https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy Product
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-48700 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.