Stored XSS in Zimbra Collaboration CalendarInvite classic webmail
CVE-2024-27443 is a cross-site scripting vulnerability in Zimbra Collaboration (ZCS) 9.0 and 10.0 affecting the CalendarInvite feature in the classic webmail user interface. The issue is caused by improper input validation and sanitization of calendar-related header data, specifically reported as handling of the calendar header and, in supporting reporting, the X-Zimbra-Calendar-Intended-For header. An attacker can send a crafted email message containing a malicious calendar header with embedded JavaScript payload. When the victim opens or views the message in the vulnerable Zimbra classic webmail interface, the payload executes in the context of the victim’s authenticated webmail session. Reporting on in-the-wild exploitation indicates the flaw has been used in zero-click-style webmail attacks where opening the email is sufficient to trigger execution of attacker-supplied JavaScript in the browser tab hosting Zimbra.
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Recent activity
24 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A cross-site scripting (XSS) vulnerability in Roundcube and Zimbra webmail platforms, exploited for zero-click attacks by APT28.
A cross-site scripting (XSS) vulnerability in Zimbra webmail that was reportedly weaponized to enable zero-click style attacks leading to credential and email data theft via injected malicious code and abuse of the webmail API.
A cross-site scripting vulnerability in Synacor Zimbra Collaboration Suite (ZCS) that can enable credential theft, inbox manipulation, and email interception.
A medium-severity cross-site scripting (XSS) vulnerability in Zimbra webmail software, allowing attackers to execute malicious JavaScript in the victim's browser session.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.