CASCACascade Atlas

Evidence dossier

CVE-2025-66376

CVE-2025-66376

62.2–79.9Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

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.

State
PUBLISHED
Published
Jan 5, 2026
Updated
Mar 19, 2026
Evidence coverage
72%
CISA KEVCatalog member

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

FIRST EPSS12.01%

2026-07-18 · v2026.06.15 · percentile 95.7%

Source stateConflict visible

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

mitreoriginal assertion
container

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.

CISA KEVoriginal assertion
observed_exploitation

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.120090000000; percentile 0.956700000000

Applicability

Cited product scope

Trace impact →
ZimbraCollaboration
[{"status": "affected", "version": "10.0", "lessThan": "10.0.18", "versionType": "custom"}, {"status": "affected", "version": "10.1", "lessThan": "10.1.13", "versionType": "custom"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*; start including 10.0.0; end excluding 10.0.18supported
Unknown vendorUnknown product
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*; start including 10.1.0; end excluding 10.1.13supported

Assessments

CVSS by origin

6.1
nvd@nist.govCVSS 3.1 · role PrimaryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
7.2
cve@mitre.orgCVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
7.2
mitreCVSS 3.1 · role unknownCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.