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Known exploited vulnerability

CVE-2025-27915

mediumCVSS 3.1 5.4In CISA KEVEPSS 4.1%Published · n/a

The short answer

CVE-2025-27915 affects n/a n/a and is rated medium (CVSS 5.4). CISA added it to the Known Exploited Vulnerabilities catalog on 2025-10-07: attackers are using it, so patch it first.

What it is

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.

Weakness: CWE-79.

Severity

5.4 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Exploited (CISA KEV)

Yes, since Oct 7, 2025

Federal due date Oct 28, 2025

EPSS, next 30 days

4.1%

Higher than 91% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Affected products

n/a. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2025-27915 being exploited?

Yes. CISA added CVE-2025-27915 to its Known Exploited Vulnerabilities catalog on 2025-10-07, with a federal remediation due date of 2025-10-28.

How do I fix CVE-2025-27915?

CISA's 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.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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