CVE-2026-66912Medium· 5.3▾ SunlitZimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email contai…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 29.2 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Nov 1.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.5%
Last analysed / modified upstream
Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email containing a malicious From header with an embedded JavaScript payload. When the victim opens the message in Classic UI and clicks Reply while composing in HTML mode with reply headers disabled, the unsanitized From header content is rendered as HTML and the JavaScript payload executes in the victim's browser, potentially allowing the attacker to steal session information or perform actions on behalf of the victim. This issue was fixed in version 10.1.21
zimbra_collaboration < 10.1.21Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-66911Medium· 5.3Stored Cross-Site Scripting in Zimbra
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