Risk Letters

Exploited vulnerability

CVE-2024-27443

TLP:CLEAR

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Zimbra Collaboration contains a cross-site scripting (XSS) vulnerability in the CalendarInvite feature of the Zimbra webmail classic user interface. An attacker can exploit this vulnerability via an email message containing a crafted calendar header, leading to the execution of arbitrary JavaScript code.

Facts

  • Vendor: Synacor
  • Product: Zimbra Collaboration Suite (ZCS)
  • CVSS: 6.1
  • EPSS (probability of exploitation within 30 days): 24.6 %
  • On CISA's Known Exploited Vulnerabilities list since: 19 May 2025
  • First known exploitation: 19 May 2025
  • CISA's deadline for US federal agencies: 9 June 2025
  • Weakness: CWE-79
  • First seen by Risk Letters: 19 May 2025

Members see which Nordic sectors the flaw hits, and what to do about it.

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Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD