Zimbra Collaboration Suite (ZCS) Authentication Bypass and Directory Traversal Remote Code Execution (RCE) Vulnerability (CVE-2022-37042)
Executive & SecOps Summary
SECOPS ASSESSMENTZimbra Collaboration Suite (ZCS) versions 8.8.15 and 9.0
Unauthenticated attackers can bypass authentication, upload malicious ZIP archives, and exploit directory traversal to write arbitrary files, leading to Remote Code Execution (RCE)
Immediately apply the official Zimbra security patches and restrict external access to the mboximport endpoint
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Follow the official Zimbra security advisory to upgrade your installation to the latest patched version. Use the following commands to update the Zimbra patch package.
# Switch to zimbra user and stop services
su - zimbra
zmcontrol stop
exit
# Update the patch package (RedHat/CentOS example)
yum clean all
yum update zimbra-patch -y
# Restart Zimbra services
su - zimbra
zmcontrol start2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, block external access to the vulnerable mboximport endpoint using a reverse proxy or web server configuration.
# Nginx configuration to block external access to mboximport
server {
listen 443 ssl;
server_name mail.yourdomain.com;
# Deny external access to the mboximport endpoint
location ~* /service/extension/backup/mboximport {
allow 127.0.0.1;
allow 10.0.0.0/8; # Allow internal admin range only
deny all;
}
}3. Log Audit & IoC Verification Commands
Run the following commands to inspect the system for unauthorized JSP files and analyze logs for exploitation attempts.
# Search for recently created or modified JSP files in the Zimbra web directory
find /opt/zimbra/jetty/webapps/zimbra/ -name '*.jsp' -mtime -30 -ls
# Audit mailbox logs for suspicious mboximport requests
grep -i 'mboximport' /opt/zimbra/log/mailbox.log | grep -E '401|403|500'Block Exploits Instantly with Managed Virtual Patching Rules
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability exists in the mboximport functionality of Zimbra Collaboration Suite (ZCS), which is designed to receive and extract ZIP archives for mailbox migration. Due to an incomplete fix for CVE-2022-27925, an authentication bypass flaw allows attackers to access this endpoint without a valid authtoken. Combined with a lack of path validation during ZIP extraction, this enables arbitrary file write via directory traversal.
2. Exploitation Mechanics & Attack Scenario
An attacker targets the mboximport servlet endpoint without providing any authentication credentials. They construct a malicious ZIP archive containing a JSP webshell payload with directory traversal sequences (e.g., ../../) in its filename. Upon receiving the HTTP POST request, the vulnerable server bypasses authentication and extracts the archive, writing the JSP webshell directly into the public web root directory (e.g., /opt/zimbra/jetty/webapps/zimbra/). The attacker then requests the uploaded JSP file to execute arbitrary OS commands.
3. Infrastructure & Business Impact
With a CVSS score of 9.8 (Critical) and inclusion in the CISA KEV catalog, this vulnerability is actively exploited in the wild. Successful exploitation grants the attacker full control over the mail server, enabling them to compromise sensitive communications, pivot into internal networks, and deploy ransomware, posing a severe threat to business operations.
Official Vendor Advisories & References
Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 has mboximport functionality that receives a ZIP archive and extracts files from it. By bypassing authentication (i.e., not having an authtoken), an attacker can upload arbitrary files to the system, leading to directory traversal and remote code execution. NOTE: this issue exists because of an incomplete fix for CVE-2022-27925.
Frequently Asked SecOps Questions (CVE-2022-37042)
FAQQ1. How critical is CVE-2022-37042 and is it actively exploited in the wild?
CVE-2022-37042 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 92.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2022-37042?
Primary impacted vendors include zimbra across zimbra_collaboration_suite. Scope summary: Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 (including environments with incomplete fixes for CVE-2022-27925)
Q3. What temporary mitigations or workarounds exist for CVE-2022-37042 before patching?
[Mitigation] Immediately apply the official Zimbra security patches and restrict external access to the mboximport endpoint Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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🔗 Related Advisories in Similar Stack (zimbra)
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