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CVE-2025-48700

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting

6.1 MEDIUMActively exploited (CISA KEV)EPSS 1.71%
  1. Published23 Jun 2025
  2. Added to CISA KEV20 Apr 2026
  3. Remediation due23 Apr 2026
Actively exploited (CISA KEV)

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that could allow attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information.

Added to KEV: 20 Apr 2026Federal remediation due: 23 Apr 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone
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≥ 10.0.0 < 10.0.12 · ≥ 10.1.0 < 10.1.4 · 8.8.15 · 9.0.0

Remediation

Fixed in
Synacor Zimbra Collaboration Suite≥ 10.0.12

References

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Frequently asked

Is CVE-2025-48700 being actively exploited?

Yes. CVE-2025-48700 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 20 Apr 2026.

How severe is CVE-2025-48700?

CVE-2025-48700 has a CVSS 3.1 base score of 6.1, rated medium. EPSS estimates a 1.71% probability of exploitation.

Which products are affected by CVE-2025-48700?

Affected products include Synacor Zimbra Collaboration Suite.

How do I fix CVE-2025-48700?

Upgrade affected software to a fixed version, for example Synacor Zimbra Collaboration Suite 10.0.12 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-48700 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.