CVE-2026-66911

Stored Cross-Site Scripting in Zimbra

Published Oct 29, 2026 CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
Zimbra is vulnerable to stored cross-site scripting (XSS) via the Content-Location MIME header in email attachments. Due to lack of sanitization of the Content-Location header, an attacker can set it to a javascript: URI. An unauthenticated remote attacker can send a crafted email to a victim; when the victim opens the email in the Zimbra web interface and clicks the attachment name, the JavaScript payload executes in the victim's browser context. This issue was fixed in version 10.1.21

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Zimbra is vulnerable to stored cross-site scripting (XSS) via the Content-Location MIME header in email attachments. Due to lack of sanitization of the Content-Location header, an attacker can set it to a javascript: URI. An unauthenticated remote attacker can send a crafted email to a victim; when the victim opens the email in the Zimbra web interface and clicks the attachment name, the JavaScript payload executes in the victim's browser context. This issue was fixed in version 10.1.21
Title Stored Cross-Site Scripting in Zimbra
First Time appeared Synacor
Synacor zimbra Collaboration
Weaknesses CWE-79
CPEs cpe:2.3:a:synacor:zimbra_collaboration:*:*:*:*:*:*:*:*
Vendors & Products Synacor
Synacor zimbra Collaboration
References
Metrics cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
CERT-PL
Published
Updated
Nov 5, 2026, 9:19 PM
Reserved
Jul 28, 2026, 12:14 PM
Status
Awaiting Analysis
Published
Oct 29, 2026, 4:18 PM
Modified
Nov 5, 2026, 10:18 PM