High · published January 5, 2026
CVSS calls it high at 7.2. It is confirmed in active exploitation. It sits in the 97.5th percentile for exploit probability.
⚡ A sneaky stored XSS lurks in Zimbra Collaboration, and it only takes a CSS @import directive in an HTML email to wreak havoc! 🔥 Think of it like a restaurant secretly adding a spicy ingredient to a dish when nobody's looking, leaving unsuspecting diners with a fiery surprise that wasn't on the menu. In this case, an attacker can slip malicious code into emails, which then executes when the recipient opens them, just like that surprise spice! This vulnerability could allow attackers to run scripts in the context of the victim's session, compromising sensitive data, manipulating accounts, or even spreading malicious content like wildfire. It’s a high-risk situation that could lead to data theft and trust issues with users.
Think of it like a restaurant secretly adding a spicy ingredient to a dish when nobody's looking, leaving unsuspecting diners with a fiery surprise that wasn't on the menu. In this case, an attacker can slip malicious code into emails, which then executes when the recipient opens them, just like that surprise spice! Zimbra Collaboration (ZCS) before versions 10.0.18 and 10.1.13 has a stored XSS vulnerability that arises from improperly handled CSS @import directives in HTML emails, enabling attackers to inject malicious scripts that execute when the email is viewed.
This vulnerability could allow attackers to run scripts in the context of the victim's session, compromising sensitive data, manipulating accounts, or even spreading malicious content like wildfire. It’s a high-risk situation that could lead to data theft and trust issues with users. To protect against this vulnerability, upgrade to ZCS versions 10.0.18 or 10.1.13 as soon as possible. Additionally, consider implementing email filtering solutions that can identify and block malicious content, as well as educating users on recognizing suspicious emails. You've got this! By following these steps, you'll keep your Zimbra Collaboration environment secure and user trust intact. 🛡️
| Product | Versions | Fixed in |
|---|---|---|
| synacor/zimbra_collaboration_suite | ≥ 10.0.0, < 10.0.18 | 10.0.18 |
| synacor/zimbra_collaboration_suite | ≥ 10.1.0, < 10.1.13 | 10.1.13 |