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A critical-severity flaw in MongoDB Server that enables unauthorized remote attackers to extract sensitive information from database memory.
Named “MongoBleed” due to its automated similarities with the notorious Heartbleed vulnerability, the defect is tracked as CVE-2025-14847 and has a CVSS score of 7.5.
The flaw is located within the MongoDB Server’s implementation of zlib message decompression. As per the announcement made on December 19, 2025, the issue is an uninitialized memory disclosure vulnerability.
When a MongoDB instance tries to decompress a specially crafted packet, a logical error permits the requester to read segments of the uninitialized heap memory.
The hazard of MongoBleed is found in the information stored in the revealed memory. As the heap is dynamic, it frequently includes remnants from previous database operations.
Successful exploitation enables an attacker to “bleed” this memory, potentially retrieving sensitive items such as plaintext credentials, session tokens, authentication keys, or customer PII that was recently processed by the server.
Importantly, this exploit does not necessitate the attacker to be authenticated. Any remote user with network access to the database port can activate the vulnerability.
The risk is further exacerbated by the fact that zlib compression is enabled by default in standard MongoDB configurations, ensuring a broad attack surface immediately upon disclosure.
As stated by the internet observability platform Censys, the exposure landscape is substantial. By late December, Censys queries found over 87,000 potentially vulnerable MongoDB instances exposed to the public internet.
The vulnerability impacts a wide array of versions, ranging from legacy deployments to the latest releases. Affected versions include:
- MongoDB 8.2: 8.2.0 – 8.2.2
- MongoDB 8.0: 8.0.0 – 8.0.16
- MongoDB 7.0: 7.0.0 – 7.0.27
- MongoDB 6.0: 6.0.0 – 6.0.26
- MongoDB 5.0: 5.0.0 – 5.0.31
- MongoDB 4.4: 4.4.0 – 4.4.29
- Legacy: All versions of 4.2, 4.0, and 3.6.
Although there is no confirmed proof of active exploitation in the wild at the time of writing, the window for applying patches is closing swiftly. A Proof-of-Concept (PoC) exploit has already been shared by a researcher, Joe Desimone, on GitHub.
The existence of public exploit code significantly increases the chances that threat actors will commence scanning for and harvesting data from unpatched servers.
MongoDB has issued patches to rectify CVE-2025-14847. Administrators are encouraged to upgrade promptly to the following versions or newer:
- 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, and 4.4.30.
For organizations that are unable to apply patches right away, temporary mitigation measures are accessible. Administrators can disable zlib compression by adjusting the networkMessageCompressors or net.compression.compressors settings to explicitly exclude zlib.
Moreover, limiting network access to trusted IP addresses is a standard best practice for database security that aids in preventing remote attackers from accessing vulnerable services.
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