CVE-2025-27915
Improper Neutralization of Input During Web Page Generation
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
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.
Official description from the CVE record, published by mitre. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org
Key data
CVSS 3.1 Medium 5.4
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Attack vector: Network
The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity: Low
No special conditions are needed. The attack can be repeated at will.
Privileges required: Low
A basic user account is needed.
User interaction: Required
A user has to do something first, such as opening a file or following a link.
Scope: Changed
The impact can reach other components beyond the vulnerable one.
Confidentiality impact: Low
Limited effect on the secrecy of data.
Integrity impact: Low
Limited effect on the trustworthiness of data.
Availability impact: None
No effect on availability.
| Metric | Value | What it means |
|---|---|---|
| Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. |
| Attack complexity | Low | No special conditions are needed. The attack can be repeated at will. |
| Privileges required | Low | A basic user account is needed. |
| User interaction | Required | A user has to do something first, such as opening a file or following a link. |
| Scope | Changed | The impact can reach other components beyond the vulnerable one. |
| Confidentiality impact | Low | Limited effect on the secrecy of data. |
| Integrity impact | Low | Limited effect on the trustworthiness of data. |
| Availability impact | None | No effect on availability. |
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EPSS
- Score
- 0.04064 (4.1% probability)
- Percentile
- 90.8%
- Scores of
- Nov 10, 2026
- Model
- v2026.06.15
CISA Known Exploited Vulnerabilities
- Name in the catalog
- Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
- Added to the catalog
- Oct 7, 2025
- Federal due date
- Oct 28, 2025
CISA assessment as of Oct 7, 2025
- Exploitation
- Recorded by CISA as active
- Automatable
- no
- Technical impact
- total
Weakness (CWE)
- CWE-79Improper Neutralization of Input During Web Page Generation
References
Timeline
- ID reserved
- Record published
- Added to CISA KEV
- Record last updated
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About CubePath
Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:53 UTC. Sources and licenses