MongoDB Exposed Uninitialized Memory in Critical Security Hole
A serious vulnerability has been discovered in MongoDB that could let attackers access sensitive, uninitialized data directly from the server's memory, even without logging in. Experts warn the flaw poses a significant risk to data security.
CVE-2025-14847: The Details
The vulnerability, identified as CVE-2025-14847, carries a CVSS score of 8.7, marking it as high-severity. Essentially, it's a case of improper handling of length parameter inconsistency. Think of it like this: the program gets confused about the actual size of the data it's handling, leading to problems.
According to the official CVE description, "Mismatched length fields in zlib compressed protocol headers may allow a read of uninitialized heap memory by an unauthenticated client." In simpler terms, if someone messes with the compressed data headers, they might be able to access bits of memory that haven't been properly set up yet, and without even needing to log in!
Which Versions Are Affected?
This flaw impacts a wide range of MongoDB versions. Here's the list:
- MongoDB 8.2.0 through 8.2.3
- MongoDB 8.0.0 through 8.0.16
- MongoDB 7.0.0 through 7.0.26
- MongoDB 6.0.0 through 6.0.26
- MongoDB 5.0.0 through 5.0.31
- MongoDB 4.4.0 through 4.4.29
- All MongoDB Server v4.2 versions
- All MongoDB Server v4.0 versions
- All MongoDB Server v3.6 versions
The Fix is In! Upgrade Now
The good news is that MongoDB has already released patched versions to address this issue. Make sure you're running one of these:
- MongoDB 8.2.3
- MongoDB 8.0.17
- MongoDB 7.0.28
- MongoDB 6.0.27
- MongoDB 5.0.32
- MongoDB 4.4.30
MongoDB themselves strongly recommends upgrading to a fixed version ASAP. "An client-side exploit of the Server's zlib implementation can return uninitialized heap memory without authenticating to the server," they warned.
Temporary Workaround: Disable zlib Compression
If you can't update immediately, you can temporarily mitigate the risk by disabling zlib compression on your MongoDB server. You can do this by starting mongod or mongos with a networkMessageCompressors or a net.compression.compressors option that explicitly excludes zlib. Alternatives like snappy and zstd are still available.
"CVE-2025-14847 allows a remote, unauthenticated attacker to trigger a condition in which the MongoDB server may return uninitialized memory from its heap," OP Innovate said. "This could result in the disclosure of sensitive in-memory data, including internal state information, pointers, or other data that may assist an attacker in further exploitation."
Bottom line: Update your MongoDB server or disable zlib compression to protect your data. Stay safe out there!
