How severe is CVE-2025-48700?

CVE-2025-48700 has a CVSS 3.1 base score of 6.1 (MEDIUM). EPSS estimates a 1.7% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2025-48700: Synacor Zimbra Collaboration Suite (ZCS) Cross-site

CISA Known Exploited Vulnerabilities

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2026-04-20

Remediation due

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.

CISA notes
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-48700

Description

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.

Severity

CVSS 3.1 · CISA6.1 MEDIUM

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

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impactpartial

Exploitation Context

as of October 15, 2026

All KEV statistics→

CISA added CVE-2025-48700 to the KEV catalog 301 days after its CVE record was published. The median for entries added in 2026 so far is 14 days.
It is one of 19 Zimbra entries in the CISA KEV catalog, and one of 5 added in 2026.
Its current EPSS score (1.7%) is higher than that of 7% of CISA KEV entries.

Affected Products

Vendor	Product	Affected versions
-	-	n/a

References

3 Links

Other references

Record Details

Published

2025-06-23

Last updated

2026-04-21

Assigner (CNA)

mitre

Credited to

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CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.