CVE-2025-27915

Exp

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.

Published: 2025-03-12 Last update: 2025-11-04 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-27915 is rated Critical Active Threat (84.2/100): CVSS Medium severity, with high exploitation likelihood (EPSS 26.05%, 96th percentile). CISA KEV confirms active exploitation (added 2025-10-07) affecting Synacor / Zimbra Collaboration Suite (ZCS). cross-site scripting (CWE-79) Unauthenticated remote administrative access may be possible. EPSS rose +3.85% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2025-27915

Name: Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability · CISA KEV detail

Exploit added: 2025-10-07

Action due: 2025-10-28

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.

Public exploit references (Exploit-DB) for CVE-2025-27915

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-27915

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-21 22.20% 26.05% +3.85%
2 2026-04-20 17.20% 22.20% +5.00%
3 2026-04-10 — 17.20% —

Full EPSS history (39 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-27915

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 2.7 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-27915

Affected software / configurations for CVE-2025-27915

Vendor Product Version Raw CPE
synacor zimbra_collaboration_suite >= 10.0.0, < 10.0.13 cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
synacor zimbra_collaboration_suite >= 10.1.0, < 10.1.5 cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:-:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p1:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p10:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p11:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p12:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p13:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p14:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p15:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p16:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p17:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p18:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p19:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p2:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p20:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p21:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p22:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p23:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24.1:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p25:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p26:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p27:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p28:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p29:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p3:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p30:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p31:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p32:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p33:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p34:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p35:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p36:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p37:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p38:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p39:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p4:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p40:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p41:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p42:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p43:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p5:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p6:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p7:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p8:*:*:*:*:*:*
synacor zimbra_collaboration_suite 9.0.0 cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p9:*:*:*:*:*:*

References for CVE-2025-27915

cvelogic Threat Intelligence