Actively exploited in the wild
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
Synacor - Zimbra Collaboration Suite (ZCS) · Listed in the CISA KEV since 2026-04-20. This indicates confirmed attacks in production environments.
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.
CVE-2025-48700
MediumCVSS 6.1KEVSummary
A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session. It arises from insufficient sanitization of HTML content, including crafted tag structures and attribute values with an @import directive. The vulnerability triggers when a user views a crafted email in the Classic UI, requiring no additional interaction.
Risk Assessment
An attacker could gain unauthorized access to sensitive information within the user's session, potentially leading to data theft or account takeover.
Recommendation
Update Zimbra Collaboration to a version containing the XSS fix and consider limiting use of the Classic UI until patched.
Other vulnerabilities in Zimbra Collaboration
See all- CVE-2016-4019High
Unspecified vulnerability in Zimbra Collaboration before version 8.7.0 allows remote attackers to affect integrity via unknown vectors.
- CVE-2016-3413High
Unspecified vulnerability in Zimbra Collaboration before 8.7.0 allows remote attackers to affect integrity via unknown vectors.
- CVE-2016-3406High
Multiple cross-site request forgery (CSRF) vulnerabilities in Zimbra Collaboration before version 8.7.0 allow remote attackers to hijack the authentication of unspecified victims via vectors involving the Client uploader extension or extension REST handlers.
- CVE-2016-3405High
Multiple unspecified vulnerabilities in Zimbra Collaboration before version 8.7.0 allow remote attackers to affect integrity.
- CVE-2016-3404High
Unspecified vulnerability in Zimbra Collaboration before 8.7.0 allows remote attackers to affect integrity via unknown vectors.
- CVE-2016-3402High
Unspecified vulnerability in Zimbra Collaboration before version 8.7.0 allows remote attackers to affect confidentiality via unknown vectors.
- CVE-2026-73570HighActively exploited
A remote code execution vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.20 when the optional zimbra-snmp package is installed and SNMP notifications are enabled. Due to improper sanitization of untrusted input during SNMP notification processing, an unauthenticated attacker can send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.
- CVE-2022-27924HighActively exploited
Zimbra Collaboration (ZCS) 8.8.15 and 9.0 allows an unauthenticated attacker to inject arbitrary memcache commands into a targeted instance. These memcache commands become unescaped, causing an overwrite of arbitrary cached entries.
- CVE-2016-3415Critical
Zimbra Collaboration before version 8.7.0 allows remote attackers to conduct deserialization attacks via unspecified vectors.
- CVE-2026-73576Medium
In Zimbra Collaboration (ZCS) before 10.1.17, there is a vulnerability involving weak cryptographic key generation in the OnlyOffice integration. The JWT secret (zimbraDocumentEditingJwtSecret) is generated using an insecure random number generator, resulting in insufficient entropy. An attacker who obtains a JWT signed with this secret may be able to recover it through offline brute-force, potentially enabling JWT forgery.
Original NVD description (English source)
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.