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CVE-2024-27443VulnerabilityAdded to KEV 05/19/2025

CVE-2024-27443: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Affects Synacor Zimbra Collaboration Suite (ZCS)Source CISA KEV

0

Exploited in the wild · KEV due 9 Jun 2025 · public detection template (Nuclei) · 24% EPSS : apply the vendor's fix or mitigations to Synacor Zimbra Collaboration Suite (ZCS) now.

Data as of 10/24/2026, 22:15:59 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.
Exploitation

Actively exploited – in CISA KEV since 05/19/2025

KEV deadline
06/09/2025 US federal agencies must patch by this date; a sensible deadline for everyone else.
EPSS
24.6% chance of exploitation in 30 days – higher than 97% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Public exploits
a Nuclei detection templatePublic attack or detection tooling exists; see Public exploits below.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

What to do

CISA 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.

Public exploits and detection

Public tooling indexed from Metasploit Framework, Exploit-DB and ProjectDiscovery nuclei-templates. Its existence raises the odds of exploitation; it does not confirm attacks.

Description

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.

Weaknesses

References

Community reviews

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