What is CVE-2025-48700?

CVE-2025-48700 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2025-06-23.

How severe is CVE-2025-48700?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2025-48700 known to be exploited?

Yes. CVE-2025-48700 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-20), indicating it is being actively exploited.

XSS in Synacor Zimbra Collaboration Suite

CVE-2025-48700

An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.017 (75.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Synacor Zimbra_collaboration_suite — versions 8.8.15, 9.0.0
N/a — versions n/a

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-04-20. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-04-23.

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.

References

cve@mitre.org (Vendor Advisory)
cve@mitre.org (Release Notes)
cve@mitre.org (Product)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2025-48700?: CVE-2025-48700 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2025-06-23.
How severe is CVE-2025-48700?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2025-48700 known to be exploited?: Yes. CVE-2025-48700 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-20), indicating it is being actively exploited.