CVE-2025-48700
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 23 April 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.71% probability · 77th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 20 April 2026 · due 23 April 2026
- Weakness
- CWE-79
- Affected
- synacor/zimbra collaboration suite
- Source
- cve@mitre.org
EPSS 1.7% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-48700
References
- https://wiki.zimbra.com/wiki/Security_CenterRelease Notes
- https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_PolicyProduct
- https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-48700US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.