CVE-2025-27915 KEV
Patch first
On CISA KEV — known exploited in the wild, due 2025-10-28.
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.
Scoring
| CVSS | 5.4 (MEDIUM, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N |
| EPSS | 3.99% — more likely to be exploited than 90% of all CVEs |
| Weakness | CWE-79 |
| On CISA KEV | yes — remediate by 2025-10-28 |
| Public exploit | none known |
| Published | 2025-03-12 |
| Last modified | 2026-06-17 |
CISA KEV
| Name | Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability |
|---|---|
| Added | 2025-10-07 |
| Due | 2025-10-28 |
| Vendor / product | Synacor / Zimbra Collaboration Suite (ZCS) |
| Ransomware use | none reported |
Affected (1)
| Vendor | Product |
|---|---|
| synacor | zimbra collaboration suite |
References
- https://wiki.zimbra.com/wiki/Security_Center
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes
- https://strikeready.com/blog/0day-ics-attack-in-the-wild/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915
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