CVE-2026-66911 json
Stored Cross-Site Scripting in Zimbra
published 2026-10-29 10 d ago modified 2026-11-05 3 d ago also EUVD-2026-112941
- cvss
- 5.3
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 45%
- public exploits
- 0
- none known
Summary
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
Patch / fix
- Synacor Zimbra Collaboration 10.1.21
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 3 d ago
Exploit prediction
0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 5.3 | 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 |
| CNA | 4.0 | 5.3 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- Synacor Zimbra Collaboration
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
cert.pl
/en/posts/2026/10/CVE-2026-66911
third-party-advisory
-
wiki.zimbra.com
/wiki/Zimbra_Security_Advisories
release-notes
Sources
- CVE List CVE-2026-66911
- NVD CVE-2026-66911
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