Loading vulnerability…
CVE-2025-66376 is a stored cross-site scripting vulnerability in Zimbra Collaboration Suite affecting ZCS 10.0 before 10.0.18 and 10.1 before 10.1.13. The flaw resides in the Classic UI handling of HTML email content and can be triggered by abusing Cascading Style Sheets @import directives embedded in an HTML message. When a victim views the crafted email in the Classic UI, attacker-controlled script can execute within the context of the authenticated webmail session. Because the payload is stored in the email content itself, exploitation can occur when the message is opened, enabling browser-side execution against the victim’s mailbox session.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
51 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Stored XSS vulnerability in Zimbra Collaboration exploited in the broader webmail campaign context via malicious HTML email and CSS @import.
A cross-site scripting vulnerability in Synacor Zimbra Collaboration Suite that was exploited in attacks against Ukrainian entities to steal credentials, tokens, 2FA data, and mailbox contents.
A Zimbra cross-site scripting vulnerability that was exploited in attacks attributed to APT28 against Ukrainian government entities.
A Zimbra XSS vulnerability that was exploited by APT28 in phishing attacks against Ukrainian government-related targets via malicious emails opened in vulnerable Zimbra webmail sessions.
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.