MongoDB Flaw Allows Unauthenticated Memory Access, Immediate Patching Required
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Key Takeaways
- Critical vulnerability: A significant security flaw has been identified in MongoDB, allowing attackers to read uninitialized heap memory from the server.
- Potential for data exposure: Sensitive data, including credentials, session tokens, and other confidential information, could be exposed if stored in the server's memory.
- Immediate patching required: MongoDB has released patches for the affected versions, and admins are urged to apply them immediately to mitigate the risk.
A critical MongoDB vulnerability has been disclosed that allows an unauthenticated remote attacker to access and read uninitialized memory on a vulnerable MongoDB server. This type of flaw can expose sensitive data fragments that may have been previously processed and are still present in the server's memory.
Technical Details of the Vulnerability
“A client-side exploit of the Server's zlib implementation can return uninitialized heap memory without authenticating to the server,” a MongoDB advisory reads. The vulnerability, tracked as CVE-2025-14847 (aka MongoBleed), stems from an issue in how the popular NoSQL database handles specific types of queries or commands.
An attacker can craft a malicious request that causes the server to return a response containing data from uninitialized heap memory. Because this action does not require authentication, any exposed MongoDB instance is a potential target.
An Elastic Security employee posted a proof-of-concept (PoC) exploit on GitHub, and Cybersecurity expert Kevin Beaumont validated it, stating that it harvests in-memory data such as:
- Database passwords (which are plain text),
- AWS secret keys.
The exploit does not allow for direct control over which memory is read, but an attacker can repeatedly query the server to collect a significant amount of data fragments over time. This information can then be pieced together to reconstruct sensitive information.
This issue affects MongoDB versions:
- 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
According to Wiz, which validated many internet-facing instances as exploitable, “42% of cloud environments have at least one instance of MongoDB in a version vulnerable to CVE-2025-14847, including both publicly exposed and internal resources,” and Censys has reported observing 87,000 potentially vulnerable instances worldwide.
Mitigation and Cybersecurity Patch Update
In response to the discovery, MongoDB has released security patches, and administrators are strongly advised to immediately apply them to all affected MongoDB instances and upgrade to 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, or 4.4.30.
“If you cannot upgrade immediately, disable zlib compression on the MongoDB Server by starting mongod or mongos with a ‘networkMessageCompressors’ or a ‘net.compression.compressors’ option that explicitly omits zlib. Example safe values include snappy,zstd or disabled,” the advisory reads.
Last week, novice researchers were targeted via GitHub repositories containing fake PoC exploits for legitimate vulnerabilities.
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