CVE-2025-66376
Confirmed PUBLISHEDZimbra 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...
1 day faster than CISA KEV
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
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.
- CVE Published
- Jan 05, 2026
- Exploitation Reported
- Jun 01, 2026
- CVSS
- 7.2 High
- EPSS
- 12.0%
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| Zimbra |
Collaboration
|
10.0 to < 10.0.18 |
Affected |
| Zimbra |
Collaboration
|
10.1 to < 10.1.13 |
Affected |
CVE References
- wiki.zimbra.com/wiki/Zimbra_Security_Advisories wiki.zimbra.com · CVE Record https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
- wiki.zimbra.com/wiki/Security_Center wiki.zimbra.com · CVE Record https://wiki.zimbra.com/wiki/Security_Center
- wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy wiki.zimbra.com · CVE Record https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy
- wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13 wiki.zimbra.com · CVE Record https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes
- wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18 wiki.zimbra.com · CVE Record https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
Known Exploited Vulnerability Sources
Catalogues that list this CVE as a known exploited vulnerability.
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CVE First | 2026-06-01 12:10 UTC |
| CISA | 2026-06-02 14:02 UTC |
No detection artifacts or sensor request patterns are available for this CVE yet.
Check back as sensor telemetry and scanner integrations are updated.
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Exploitation Status
Exploited in the wild
Recorded 2026-06-01 12:10:26 UTC · CVE
Weaknesses (CWE)
-
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
14:02 UTC about 2 months ago14:02 UTC · about 2 months ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
12:10 UTC about 2 months ago12:10 UTC · about 2 months ago
Added to KEVIntel KEV Feed
High-confidence, third-party attested exploitation
-
00:00 UTC 7 months ago00:00 UTC · 7 months ago
CVE published
Vulnerability disclosed publicly
-
00:00 UTC 8 months ago00:00 UTC · 8 months ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2025-66376
{
"cve_id": "CVE-2025-66376",
"title": "Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows C...",
"affected_vendor": "Zimbra",
"affected_product": "Collaboration",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 7.2,
"epss_score": 0.12009,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}