Synacor

CVE-2026-66911: 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-

CVE-2026-66911 Oct 29, 2026 Source: Vendor

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

Source of record The credited names below are quoted verbatim from the vendor's own advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-66911

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Credited

2 lines

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CVE-2026-66911 BR2026-0000-038285 unclaimed

Credited as Suraj Disoja (TrustFoundry)

CVE-2026-66911 BR2026-0000-038286 unclaimed

Credited as Mateusz Borkowski (CERT.PL)