CVE-2025-27915An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1.
Updated under an hour ago ()
Does this affect you?
It affects synacor zimbra_collaboration_suite. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Oct 7, 2025; federal agencies had to remediate by Oct 28, 2025. Treat that date as your deadline.
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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
- 5.4 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- Weakness (CWE)
- CWE-79
- Known exploited
- Added to CISA KEV Oct 7, 2025; federal remediation due Oct 28, 2025Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- EPSS (exploitation in the next 30 days)
- 4.06% (percentile 91)
- Assigned by
- mitre
- NVD analysis
- Analyzed
- Record last updated
- Feb 26, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
synacor zimbra_collaboration_suite synacor:zimbra_collaboration_suite | from 10.0.0 before 10.0.13; from 10.1.0 before 10.1.5; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; and 39 more ranges | NVD |
References
- https://wiki.zimbra.com/wiki/Security_Centerrelease-notes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixesrelease-notes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixesrelease-notes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixesrelease-notes
- https://strikeready.com/blog/0day-ics-attack-in-the-wild/exploit, third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.