BLACKOUT MAP

Synacor · Zimbra Collaboration Suite (ZCS)

CVE-2025-48700

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability

Exploited in attacks Medium 6.1 Attack chance: 1.7%
Share

What it is

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.

CISA: 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.

What to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Deadline for US federal agencies: April 23, 2026

Added to the CISA list
April 20, 2026
Published
June 23, 2025
Severity
Medium 6.1 CVSS 3.1
Chance of attacks in the next 30 days (EPSS)
1.7% in the top 22.7% of all known vulnerabilities
Weakness
CWE-79
More details
NVD · CVE.org · CISA
All references (3)

More exploited flaws from Synacor

AddedVulnerabilityProductSeverityAttack chance
Aug 21, 2026OS Command InjectionCVE-2026-73570Zimbra Collaboration Suite (ZCS)High 8.972%
Mar 18, 2026Cross-Site ScriptingCVE-2025-66376Zimbra Collaboration Suite (ZCS)High 7.220%
Oct 7, 2025Cross-site ScriptingCVE-2025-27915Zimbra Collaboration Suite (ZCS)Medium 5.44.1%
Jul 7, 2025Server-Side Request Forgery (SSRF)CVE-2019-9621Zimbra Collaboration Suite (ZCS)High 7.581%
May 19, 2025Cross-Site Scripting (XSS)CVE-2024-27443Zimbra Collaboration Suite (ZCS)Medium 6.125%
Feb 25, 2025Cross-Site Scripting (XSS)CVE-2023-34192Zimbra Collaboration Suite (ZCS)Critical 9.077%
Oct 3, 2024Command ExecutionCVE-2024-45519Zimbra Collaboration Suite (ZCS)Critical 10.099.9%
Jul 27, 2023Cross-Site Scripting (XSS)CVE-2023-37580Zimbra Collaboration Suite (ZCS)Medium 6.149%

All of them →

Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.