CVE-2026-33370Network attack vector

Stored XSS via unsanitized inline XML rendering

Published Mar 20, 2026 · Updated Mar 20, 2026

Stored XSS in Zimbra Collaboration 10.0 and 10.1 allows remote attackers to execute scripts when a user opens a public Briefcase file. The Briefcase download path renders certain uploaded XML content inline without applying defang sanitization, so embedded JavaScript runs in the viewer session. Exploitation requires a victim to open an attacker-controlled publicly shared file and permits session-context data access and actions, but no service interruption is reported.

CVSS severity6.1
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Zimbra Collaboration 10.0 and 10.1 allows remote attackers to execute scripts when a user opens a public Briefcase file. The Briefcase download path renders certain uploaded XML content inline without applying defang sanitization, so embedded JavaScript runs in the viewer session. Exploitation requires a victim to open an attacker-controlled publicly shared file and permits session-context data access and actions, but no service interruption is reported.

The record

CVE
CVE-2026-33370
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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