What is the CVSS score of CVE-2025-27915?

CVE-2025-27915 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 22.9%.

Which versions of Zimbra Collaboration Suite are affected by CVE-2025-27915?

CVE-2025-27915 presents moderate security risk, a cross-site scripting vulnerability rated CVSS 5.4. Attackers could inject scripts to steal sessions or perform actions as authenticated users.

Is there a public PoC exploit available for CVE-2025-27915?

Yes, a public proof-of-concept exploit is available for CVE-2025-27915. Prioritise patching immediately. EPSS: 22.9%.

How to fix or mitigate CVE-2025-27915?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Zimbra Collaboration Suite CVE-2025-27915

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2025-03-12 cve@mitre.org

XSS Zimbra Collaboration Suite

5.4

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

5.4 MEDIUM

AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:31 vuln.today

Added to CISA KEV

Nov 04, 2025 - 16:45 cisa

CISA KEV

PoC Detected

Nov 04, 2025 - 16:45 vuln.today

Public exploit code

CVE Published

Mar 12, 2025 - 15:15 nvd

MEDIUM 5.4

DescriptionCVE.org

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.

AnalysisAI

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. Actively exploited in the wild (cisa kev) and public exploit code available.

Technical ContextAI

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. 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. Affected products include: Synacor Zimbra Collaboration Suite.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.