Zimbra Collaboration Suite 9.0/10.0/10.1 ICS File cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Zimbra Collaboration Suite 9.0/10.0/10.1. The impacted element is an unknown function of the component ICS File Handler. Performing a manipulation results in cross site scripting. This vulnerability is cataloged as CVE-2025-27915. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Zimbra Collaboration Suite 9.0/10.0/10.1. This affects an unknown functionality of the component ICS File Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE 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 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.

It is possible to read the advisory at wiki.zimbra.com. This vulnerability is uniquely identified as CVE-2025-27915 since 03/10/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

It is declared as attacked. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 10/07/2025 with a due date of 10/28/2025:

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

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Zero-Day.cz (1037) and EUVD (EUVD-2025-7823). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Groupware Software

Vendor

• Zimbra

Name

• Collaboration Suite

Version

• 9.0
• 10.0
• 10.1

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CPE 2.2info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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