rishi-kaul/cve-2025-14847-mongobleedAnalysis and remediation guide for CVE-2025-14847 (MongoBleed), a MongoDB zlib compression memory disclosure. Includes detection indicators, mitigation steps, and patching guidance.
CVE-2025-14847, commonly referred to as MongoBleed, is a high-severity information disclosure vulnerability affecting :contentReference[oaicite:0]{index=0} Server.
The vulnerability allows a remote, unauthenticated attacker to leak sensitive data from server memory by exploiting improper handling of zlib-compressed network messages.
The issue is actively exploited in the wild and impacts MongoDB deployments using the default compression configuration.
MongoDB supports network message compression using zlib, which is enabled by default.
The vulnerability exists in the zlib decompression logic where MongoDB incorrectly returns the size of the allocated output buffer instead of the actual decompressed data length.
When malformed compressed packets are sent:
The vulnerable code path is reachable prior to authentication, making both internet-exposed and internally reachable servers vulnerable.
Successful exploitation may lead to disclosure of:
Although individual memory leaks may appear fragmented or incomplete, sustained exploitation increases the likelihood of meaningful data exposure.
The vulnerability affects MongoDB Server versions prior to the following patched releases:
| MongoDB Branch | Fixed Version |
|---|---|
| 8.2 | 8.2.3 |
| 8.0 | 8.0.17 |
| 7.0 | 7.0.28 |
| 6.0 | 6.0.27 |
| 5.0 | 5.0.32 |
| 4.4 | 4.4.30 |
MongoDB Atlas deployments have already been patched.
Monitor MongoDB server logs for suspicious or unexpected activity occurring before authentication, which may indicate probing, malformed handshakes, or exploitation attempts.
Focus on log entries related to:
Use the following command to filter relevant indicators from MongoDB logs:
bash
grep -Ei "compress|decompress|zlib|handshake|authentication" /var/log/mongodb/mongod.log"""
Repeated decompression errors from the same source
High connection volume without authentication success
Malformed packet errors preceding login attempts
Suspicious activity may include:
Repeated short-lived TCP connections to port 27017
Abnormal compressed payload patterns
Lack of corresponding authentication events
Relevant telemetry sources:
Firewall and IDS/IPS logs
VPC Flow Logs
Network monitoring tools (e.g., Zeek, Suricata)
MongoDB should not be directly accessible from untrusted networks.
Remove public exposure
Enforce firewall and security group restrictions
Limit access to known application hosts only
Disabling zlib compression removes the vulnerable code path until patching is completed.
Configuration example:
net compression:
compressors: snappy
Or via command line:
mongod --networkMessageCompressors snappy
Upgrade MongoDB to a patched version listed above.
Given the nature of the vulnerability (memory disclosure), assume potential exposure if the server was reachable.
Recommended follow-up actions:
Rotate MongoDB user credentials
Rotate application secrets and API keys
Review historical logs for suspicious activity
Strengthen monitoring for pre-authentication anomalies
Advisory Status
CVE-2025-14847 has been added to the CISA Known Exploited Vulnerabilities (KEV) Catalog, confirming real-world exploitation and increasing remediation priority.