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Vulnerabilities

Vulnerability · CVE-2025-48700

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability

Published Jun 23, 2025 · catalog updated Jun 17, 2026 · Synacor Zimbra Collaboration Suite (ZCS)

Patch now

CVE-2025-48700 is in the CISA known-exploited catalog, due Apr 23, 2026. Confirm Synacor Zimbra Collaboration Suite (ZCS) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
Medium6.1
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
1.71%
Remediation
Remediation guidance
Affected products
cpe synacor/zimbra collaboration suite · vendor Synacor Zimbra Collaboration Suite (ZCS)

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe synacor/zimbra collaboration suite8.8.15
  • vendor Synacor Zimbra Collaboration Suite (ZCS)version unspecified

How to fix CVE-2025-48700

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2025-48700 is in the CISA known-exploited catalog, due Apr 23, 2026. Confirm Synacor Zimbra Collaboration Suite (ZCS) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with synacor/zimbra collaboration suite 8.8.15. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 1.71%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 23, 2025 · Catalog

    Detected

    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 ta

  2. Apr 20, 2026 · CISA KEV

    Known exploited

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

  3. Apr 23, 2026 · CISA KEV

    Remediation due

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

  4. Jun 17, 2026 · Catalog

    Updated

    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 ta

Sources

  • CISA KEVConfirmed exploitationCVE-2025-48700

    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.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2025-48700

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-48700

    30-day exploitation probability 1.7%

    first.org
  • NIST NVDVulnerability recordCVE-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 se

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2025-48700

    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.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.