Session data theft via unsanitized ICS event handlers
Published Mar 12, 2025 · Updated Feb 26, 2026
Stored XSS in Zimbra Collaboration 9.0, 10.0, and 10.1 allows remote authenticated users to execute JavaScript via a crafted ICS entry. The Classic Web Client fails to sanitize HTML from ICS content, permitting an ontoggle handler inside a details element to run when the message is viewed. Viewing the malicious email is required; code runs in the victim's session and can redirect or exfiltrate email.
Summary
What happened
Stored XSS in Zimbra Collaboration 9.0, 10.0, and 10.1 allows remote authenticated users to execute JavaScript via a crafted ICS entry. The Classic Web Client fails to sanitize HTML from ICS content, permitting an ontoggle handler inside a details element to run when the message is viewed. Viewing the malicious email is required; code runs in the victim's session and can redirect or exfiltrate email.
The record
- CVE
- CVE-2025-27915
- Published
- Mar 12, 2025
- Updated
- Feb 26, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-79, T1203
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 12, 2025CVE publishedPublication date reported by the CVE source.
- Oct 7, 2025Exploitation reportedCISA Known Exploited Vulnerabilities listing
- Feb 26, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Malicious ICS and deobfuscated JavaScript artifactsweaponized · observed in use
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Reported exploitation
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
- Malicious ICS campaign targeting Brazil's militaryreported exploitation
Technologies
Your stack
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Your stack
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