CVEvulnerability

CVE-2025-66376

6.1 MEDIUM Known exploited Published 2026-01-05 Modified 2026-10-07 Official page ↗

CISA Known Exploited Vulnerability

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability — Synacor Zimbra Collaboration Suite (ZCS)

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability in the Classic UI where attackers could abuse Cascading Style Sheets (CSS) @import directives in email HTML.

Added to KEV: 2026-03-18
Remediation due: 2026-04-01
Ransomware use: 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.
Notes: https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-66376

Status: Analyzed
Published: 2026-01-05
Last modified: 2026-10-07
Assigner: [email protected]
CVSS 3.1 ([email protected]): 7.2 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
CVSS 3.1 ([email protected]): 6.1 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weaknesses: CWE-79

Description

Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.

Affected configurations

• synacor zimbra collaboration suite (>= 10.0.0 < 10.0.18) • synacor zimbra collaboration suite (>= 10.1.0 < 10.1.13)

Weakness · CWE (1)

CWE-79 Improper Neutralization of Input During Web Page Generation weakness

References