CVE-2025-53645
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to cause denial of service in Zimbra Collaboration Suite by sending specially crafted GET requests with excessive comma-separated path segments to the Admin Console. The improper handling triggers redundant processing and inflated responses, leading to uncontrolled resource consumption. Organizations running vulnerable Zimbra versions with exposed Admin Consoles are affected.
💻 Affected Systems
- Zimbra Collaboration Suite
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage of Zimbra Collaboration Suite, rendering email, calendar, and collaboration services unavailable to all users until system recovery.
Likely Case
Degraded performance or temporary service disruption of the Admin Console and potentially other Zimbra services due to resource exhaustion.
If Mitigated
Minimal impact with proper network segmentation and rate limiting preventing exploitation attempts from reaching vulnerable systems.
🎯 Exploit Status
Exploitation requires sending specially crafted GET requests with excessive comma-separated path segments to the Admin Console endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.0.0 Patch 46, 10.0.15, or 10.1.9
Vendor Advisory: https://wiki.zimbra.com/wiki/Security_Center
Restart Required: Yes
Instructions:
1. Download the appropriate patch from Zimbra's official repository. 2. Apply the patch following Zimbra's upgrade documentation. 3. Restart Zimbra services. 4. Verify the patch is applied correctly.
🔧 Temporary Workarounds
Restrict Admin Console Access
linuxLimit access to the Admin Console to trusted IP addresses only using firewall rules.
iptables -A INPUT -p tcp --dport 7071 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 7071 -j DROP
Implement Rate Limiting
allConfigure web server or application firewall to limit request rates to the Admin Console endpoint.
# Configure in nginx: limit_req_zone $binary_remote_addr zone=admin:10m rate=10r/s;
# Then apply to Admin Console location
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the Admin Console from untrusted networks
- Deploy a WAF with DoS protection rules specifically for the Admin Console endpoint
🔍 How to Verify
Check if Vulnerable:
Check Zimbra version using 'zmcontrol -v' and compare against vulnerable versions. Also verify if Admin Console is accessible from untrusted networks.Check Version:
zmcontrol -vVerify Fix Applied:
After patching, verify version shows patched version and test that crafted requests no longer cause resource exhaustion.📡 Detection & Monitoring
Log Indicators:
- Unusually high number of GET requests to Admin Console with comma-separated paths
- Increased CPU/memory usage logs from Zimbra services
- Error logs indicating request processing failures
Network Indicators:
- Multiple rapid GET requests to /zimbraAdmin/ with comma-separated path segments
- Unusual traffic patterns to port 7071 (default Admin Console port)
SIEM Query:
source="zimbra.log" AND "GET /zimbraAdmin/" AND path CONTAINS ","🔗 References
- https://wiki.zimbra.com/wiki/Security_Center
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.15#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.9#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P46#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
