CVE-2025-66376

Analyzed
Published: 05 Jan 2026, 00:00
Last modified:19 Mar 2026, 03:55

Vulnerability Summary

Overall Risk (default)
medium
29/100
CVSS Score
7.2 HIGH
v3.1 (cve.org)
EPSS Score
0.05% LOW
0% probability 0.00%
KEV
Listed
CISA
1 listing
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

05 Jan 2026, 00:00
Published
Vulnerability first disclosed
18 Mar 2026, 00:00
Added to CISA KEV
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
19 Mar 2026, 03:55
Last Modified
Vulnerability information updated
01 Apr 2026, 00:00
CISA 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.

Description

Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.

CVSS Metrics

  • v3.1•HIGH•Score: 7.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
  • v3.1•MEDIUM•Score: 6.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Trends

Current EPSS score: 0.05%• Percentile: 15%

Techniques & Countermeasures

  • CWE-79•Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

    The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Affected Systems

  • synacor•zimbra_collaboration_suite

    ≥ 10.0.0, < 10.0.18 | ≥ 10.1.0, < 10.1.13

  • zimbra•collaboration

    ≥ 10.0, < 10.0.18 | ≥ 10.1, < 10.1.13

References (6)