CVE-2024-27443
MediumExploitedPublic exploitA 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.
Published Aug 12, 2024 · Updated Aug 12, 2026
Key Facts
Patch immediately- CVE-2024-27443 is a medium-severity vulnerability (CVSS 6.1 v3.1) affecting Collaboration (Zimbra).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 15, 2025. Public exploit code is available.
- EPSS estimates a 25% probability of exploitation in the next 30 days.
- Fixed versions are available, including Collaboration 10.0.7.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS (30-day exploit likelihood)
25%
Higher than 97.8% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | May 19, 2025 | Jun 9, 2025 | Not reported |
| Industry KEV feed | May 15, 2025 | Jun 9, 2025 | Not reported |
| CIRCL KEV | May 19, 2025 | Jun 9, 2025 | Not reported |
| ENISA EUVD | May 19, 2025 | n/a | Not reported |
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.
Affected Products
38 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| CollaborationZimbra | 9.0.0, 9.0.0-p0, 9.0.0-p1, 9.0.0-p10, 9.0.0-p11, 9.0.0-p12, 9.0.0-p13, 9.0.0-p14 | 10.0.7 |
Patched Releases
Collaboration
10.0.7
Timeline
Publicly disclosed
Aug 12, 2024
Added to Industry KEV feed
May 15, 2025
Added to CISA KEV
May 19, 2025
Added to CIRCL KEV
May 19, 2025
Added to ENISA EUVD
May 19, 2025
Last updated
Aug 12, 2026
Weakness Type
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
References
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27443.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2024-27443
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0.
Affected: Collaboration (Zimbra) versions 9.0.0, 9.0.0-p0, 9.0.0-p1, 9.0.0-p10, 9.0.0-p11, 9.0.0-p12, 9.0.0-p13, 9.0.0-p14. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 15, 2025.
Yes. It was added on May 19, 2025 with a federal remediation due date of Jun 9, 2025.
Public exploit code is available.
Fixed versions are available, including Collaboration 10.0.7.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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