CVE-2024-45518 Overview
CVE-2024-45518 is a Server-Side Request Forgery (SSRF) vulnerability affecting Zimbra Collaboration Suite (ZCS). The flaw exists in versions 10.1.x before 10.1.1, 10.0.x before 10.0.9, 9.0.0 before Patch 41, and 8.8.15 before Patch 46. Authenticated users can exploit improper input sanitization and misconfigured domain whitelisting to send unauthorized HTTP requests to internal services. Attackers can chain the SSRF with command injection in internal services to achieve Remote Code Execution (RCE). Combined with existing Cross-Site Scripting (XSS) vulnerabilities, the flaw provides additional paths to RCE. The vulnerability maps to [CWE-918] Server-Side Request Forgery.
Critical Impact
Authenticated attackers can pivot from an SSRF primitive to Remote Code Execution on the Zimbra host, exposing internal services and mailbox data.
Affected Products
- Zimbra Collaboration 8.8.15 before Patch 46
- Zimbra Collaboration 9.0.0 before Patch 41
- Zimbra Collaboration 10.0.x before 10.0.9 and 10.1.x before 10.1.1
Discovery Timeline
- 2024-10-22 - CVE-2024-45518 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-45518
Vulnerability Analysis
The vulnerability resides in Zimbra Collaboration components that accept URL or host parameters from authenticated users. Improper input sanitization combined with misconfigured domain whitelisting allows an attacker to coerce the server into issuing arbitrary HTTP requests. These requests originate from the Zimbra host and reach internal services normally shielded from external clients.
An authenticated attacker can direct these requests toward internal endpoints that perform sensitive operations. Chaining the SSRF with command injection in a reachable internal service yields Remote Code Execution under the Zimbra service account. The EPSS score of 20.176% and 97.213 percentile indicate a high probability of exploitation attempts relative to other published CVEs.
Root Cause
The root cause is a combination of insufficient input validation on user-supplied URLs and permissive domain whitelisting that fails to restrict outbound requests to trusted destinations. Requests intended for external, whitelisted hosts can be redirected or crafted to target internal services because host verification is inconsistent with the actual HTTP fetch logic.
Attack Vector
Exploitation requires network access to the Zimbra web interface and valid, low-privilege credentials. The attacker submits a crafted parameter carrying a URL that bypasses the whitelist filter and points to an internal service. The Zimbra server issues the request, and the response is either returned to the attacker or triggers command execution on the internal component. When paired with a stored or reflected XSS payload, the attack can be delivered through a victim's authenticated session without requiring the attacker to hold credentials directly.
The vulnerability is described in prose rather than exploit code. Refer to the Zimbra Security Advisories for vendor-provided technical context.
Detection Methods for CVE-2024-45518
Indicators of Compromise
- Outbound HTTP requests from the Zimbra server process to internal RFC1918 addresses, loopback, or link-local ranges that fall outside the documented integration list.
- Unexpected child processes spawned by Zimbra service accounts (zimbra, zextras), particularly shells, curl, wget, or scripting interpreters.
- Zimbra proxy or mailbox logs showing requests containing URL parameters with non-whitelisted hosts, IP-encoded destinations, or DNS rebinding artifacts.
- New or modified files under Zimbra web directories, cron entries, or JSP/JSPX files not associated with a legitimate patch cycle.
Detection Strategies
- Baseline Zimbra outbound network behavior and alert on connections to internal subnets or unusual ports originating from the mailbox or proxy service.
- Inspect Zimbra access logs (/opt/zimbra/log/) for suspicious query parameters carrying URLs, especially requests from low-privilege accounts followed by internal service activity.
- Correlate authenticated Zimbra sessions with subsequent command execution on the host to identify SSRF-to-RCE chains.
Monitoring Recommendations
- Forward Zimbra web, mailbox, and audit logs to a centralized analytics platform for retention and query.
- Monitor process ancestry on Zimbra hosts and flag interactive shells or network tools launched by web service processes.
- Track patch level of all Zimbra nodes and alert when a host falls behind the vendor security baseline.
How to Mitigate CVE-2024-45518
Immediate Actions Required
- Upgrade Zimbra Collaboration to 10.1.1, 10.0.9, 9.0.0 Patch 41, or 8.8.15 Patch 46, matching the appropriate branch.
- Rotate credentials for any Zimbra accounts that could have been used to reach the vulnerable endpoints prior to patching.
- Review Zimbra host and mailbox logs for the indicators listed above and investigate any anomalous outbound requests.
- Restrict administrative interfaces and internal service endpoints from being reachable by the Zimbra web tier where operationally feasible.
Patch Information
Zimbra released fixes in the following builds: Zimbra 10.1.1 Security Fixes, Zimbra 10.0.9 Security Fixes, Zimbra 9.0.0 Patch 41 Security Fixes, and Zimbra 8.8.15 Patch 46 Security Fixes. Consolidated vendor guidance is published in the Zimbra Security Center.
Workarounds
- Place the Zimbra web interface behind a reverse proxy or web application firewall that blocks requests containing URL parameters referencing internal address ranges.
- Use host-based firewall rules to prevent the Zimbra service account from initiating outbound connections to internal management ports and non-required destinations.
- Enforce network segmentation so that internal services cannot be reached from the Zimbra host except through explicitly required, authenticated channels.
# Example egress restriction: block Zimbra service from reaching internal ranges
# Adjust interfaces, UIDs, and address ranges to match your environment
iptables -A OUTPUT -m owner --uid-owner zimbra -d 127.0.0.0/8 -j REJECT
iptables -A OUTPUT -m owner --uid-owner zimbra -d 10.0.0.0/8 -j REJECT
iptables -A OUTPUT -m owner --uid-owner zimbra -d 172.16.0.0/12 -j REJECT
iptables -A OUTPUT -m owner --uid-owner zimbra -d 192.168.0.0/16 -j REJECT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
