CVE-2026-66912
MEDIUM
MEDIUM
Priority: 0.00
BB Relevance:
61/100
Published: 2026-10-29
Modified: 2026-10-29
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
Passive
S:
X
AT:
None
VC:
None
VI:
None
VA:
None
Description
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
Weakness Classification (1)
Affected Software (1)
| Vendor | Product | Version |
|---|---|---|
| Synacor | Zimbra Collaboration | 0 < 10.1.21 |
References & Advisories (2)
third-party-advisory
release-notes