CVE-2025-27915
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National Vulnerability Database Information
Description: 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.
CVSS Base Score: 5.4 (v3.1)
The **CVSS Base Score** is a score from **0 to 10** that represents the intrinsic severity of a vulnerability. A higher score indicates greater severity.
0.02.55.07.510.0
Published on: 03/12/2025 15:15:39
Last modified: 11/04/2025 16:45:11
NIST: CVE source from the National Vulnerability Database (NVD)
CVSS Metrics Details
- Base Severity: MEDIUM
- Vector String: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: LOW
- User Interaction: REQUIRED
- Scope: CHANGED
- Confidentiality Impact: LOW
- Integrity Impact: LOW
- Availability Impact: NONE
Common Weakness Enumeration (CWE)
Database CWE: v4.18
Fonte: MITRE CWE
FIRST Information
EPSS Score: 0.2652
The **EPSS (Exploit Prediction Scoring System)** is a score from **0 to 1** that indicates the **probability** that a vulnerability will be exploited in the real world in the next 30 days. A higher value indicates a greater likelihood of exploitation.
0.00.250.50.751.0
Percentile: 0.9616
The **Percentile** indicates how much higher this vulnerability's EPSS score is compared to all other vulnerabilities in the EPSS database. For example, a percentile of 0.90 (90%) means that 90% of vulnerabilities have an EPSS score equal to or lower than the current one.
0.00.250.50.751.0
*Data updated as of: 2026-01-15
CISA Information (Known Exploited Vulnerabilities)
The **CISA KEV Catalog** lists vulnerabilities that have been **actively exploited in the real world**. If a CVE is present in this catalog, it indicates that the threat is immediate and mitigation should be a top priority.
CVE **CVE-2025-27915** **IS PRESENT** in the CISA KEV Catalog!
- Vulnerability Name: Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
- Short Description: Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that 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 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.
- Date Added to KEV: 10/07/2025
- Vendor/Product: Synacor / Zimbra Collaboration Suite (ZCS)
- 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.
- Due Date: 10/28/2025
Articles published on Red Hot Cyber
Exploit PoC from GitHub
No results found on GitHub for this CVE.
