What is MongoBleed?
MongoBleed (CVE-2025-14847) is a high-severity information disclosure vulnerability discovered in MongoDB's network transport layer. This flaw allows unauthenticated, remote attackers to read uninitialized heap memory from affected MongoDB servers.
How Does It Work?
The vulnerability arises from improper handling of length parameter inconsistencies in the zlib compression protocol headers during decompression. When zlib compression is enabled (which is the default in many configurations), an attacker can craft malicious requests that cause the server to leak sensitive heap memory.
The attack occurs before authentication, meaning no credentials are needed to exploit it.
Affected Versions
The following MongoDB versions are vulnerable:
- 8.2.0 to 8.2.2
- 8.0.0 to 8.0.16
- 7.0.0 to 7.0.27
- 6.0.0 to 6.0.26
- 5.0.0 to 5.0.31
- 4.4.0 to 4.4.29
- All versions of 4.2, 4.0, and 3.6 series
What Data Is At Risk?
Because the vulnerability leaks uninitialized heap memory, attackers may be able to extract:
- Database credentials
- Session tokens
- Application secrets stored in memory
- Query data from other connections
- Internal configuration details
Remediation Steps
**1. Upgrade MongoDB immediately** to one of these patched versions:
# Patched versions
8.2.3
8.0.17
7.0.28
6.0.27
5.0.32
4.4.30**2. If immediate upgrade is not possible**, disable zlib compression:
# mongod.conf
net:
compression:
compressors: snappy,zstd**3. Restrict network access** to MongoDB using firewalls or security groups. Never expose MongoDB directly to the internet.
Detection
Monitor your MongoDB logs for unusual connection patterns or repeated failed decompression attempts. Implement network monitoring to detect potential exploitation attempts.
Key Takeaways
- Always keep MongoDB updated to the latest security patches
- Never expose database ports directly to the internet
- Use network segmentation and firewalls
- Enable authentication and use strong credentials
- Regularly audit your MongoDB configuration