CVE-2023-37580 in Zimbra Collaboration Suite
Summary
by MITRE • 07/31/2023
Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.
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Analysis
by VulDB Data Team • 04/24/2025
The vulnerability CVE-2023-37580 affects Zimbra Collaboration Suite version 8 before 8.8.15 Patch 41, specifically within the Zimbra Classic Web Client interface. This represents a cross-site scripting vulnerability that could potentially allow attackers to execute malicious scripts in the context of a victim's browser session. The flaw exists in the web client component of the email collaboration platform, which is widely used by enterprises for email, calendar, and collaboration services. Organizations relying on this legacy version face significant security risks as the vulnerability could be exploited to compromise user sessions and access sensitive data.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output encoding within the Zimbra Classic Web Client. Attackers can craft malicious payloads that get executed when legitimate users view affected content, typically through email messages or calendar entries. The vulnerability allows for both reflected and stored XSS scenarios, meaning malicious scripts can be injected through crafted URLs or persisted within the application's database. This flaw falls under CWE-79 - Improper Neutralization of Input During Web Page Generation, which is a fundamental weakness in web application security where user-provided data is not properly sanitized before being rendered in web pages. The vulnerability's impact is amplified by the widespread use of Zimbra in enterprise environments where users may have elevated privileges and access to sensitive organizational data.
The operational impact of this vulnerability extends beyond simple script execution as it can lead to full session hijacking, data exfiltration, and privilege escalation within the Zimbra environment. An attacker could potentially steal authentication cookies, access user mailboxes, modify calendar entries, or even gain access to administrative functions if the victim has elevated privileges. This vulnerability aligns with ATT&CK technique T1531 - Account Access Removal, as it could enable attackers to maintain persistent access to user accounts through session manipulation. The risk is particularly elevated in enterprise environments where Zimbra serves as a primary communication platform and where users may have access to confidential business information, intellectual property, or customer data.
Organizations should immediately implement the vendor-provided patch 41 for Zimbra Collaboration Suite 8.8.15 to remediate this vulnerability. In environments where patching is not immediately feasible, temporary mitigations include implementing strict content security policies, disabling potentially vulnerable features, and monitoring for suspicious user activities. Network-level protections such as web application firewalls can provide additional defense in depth, though they should not be considered a substitute for proper patching. Security teams should also conduct thorough vulnerability assessments to identify any potential exploitation attempts and implement monitoring for suspicious email content or calendar entries that might indicate attempts to leverage this vulnerability. The incident response plan should include procedures for user session termination and credential rotation if compromise is suspected.