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Fencer Intel
high 7.2

CVE-2025-66376 kev in the critical feed json

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…

published 10mo ago modified last mo. also EUVD-2026-0850

cvss
7.2
version 3.1, CNA
cisa kev
Exploited
added 2026-03-18
epss
20.2%
EPSS 20.2% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known

Summary

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.

Patch / fix

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.

  • Zimbra Collaboration 10.0.18, 10.1.13

Is CVE-2025-66376 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Timeline

  1. Published
  2. CISA SSVC: exploitation active
  3. Added to CISA KEV
  4. CISA patch deadline

Known exploited

Added
7mo ago
Patch by
2026-04-01 (7mo ago)
Ransomware
Not known
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.
Vendor, product
Synacor, Zimbra Collaboration Suite (ZCS)
CISA name
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

20.23% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

  • Zimbra Collaboration

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.