Known exploited vulnerability
CVE-2024-27443
The short answer
CVE-2024-27443 affects n/a n/a and is rated medium (CVSS 6.1). CISA added it to the Known Exploited Vulnerabilities catalog on 2025-05-19: attackers are using it, so patch it first.
What it is
An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.
Weakness: CWE-79.
Severity
6.1 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Exploited (CISA KEV)
Yes, since May 19, 2025
Federal due date Jun 9, 2025
EPSS, next 30 days
25%
Higher than 98% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- Low
- Integrity impact
- Low
- Availability impact
- None
What CISA says to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected products
n/a. NVD's record lists the exact affected versions.
References
- wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes Release Notes
- wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes Release Notes
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-27443 US Government Resource
- www.welivesecurity.com/en/eset-research/operation-roundpress/ Press/Media Coverage
Questions
Is CVE-2024-27443 being exploited?
Yes. CISA added CVE-2024-27443 to its Known Exploited Vulnerabilities catalog on 2025-05-19, with a federal remediation due date of 2025-06-09.
How do I fix CVE-2024-27443?
CISA's 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.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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