MongoDB Server Uninit Heap Read via Zlib Header Len Mismatch <4.2.0
CVE-2025-14847 Published on December 19, 2025
Zlib compressed protocol header length confusion may allow memory read
Mismatched length fields in Zlib compressed protocol headers may allow a read of uninitialized heap memory by an unauthenticated client. This issue affects all MongoDB Server v7.0 prior to 7.0.28 versions, MongoDB Server v8.0 versions prior to 8.0.17, MongoDB Server v8.2 versions prior to 8.2.3, MongoDB Server v6.0 versions prior to 6.0.27, MongoDB Server v5.0 versions prior to 5.0.32, MongoDB Server v4.4 versions prior to 4.4.30, MongoDB Server v4.2 versions greater than or equal to 4.2.0, MongoDB Server v4.0 versions greater than or equal to 4.0.0, and MongoDB Server v3.6 versions greater than or equal to 3.6.0.
Known Exploited Vulnerability
This MongoDB and MongoDB Server Improper Handling of Length Parameter Inconsistency Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. MongoDB Server contains an improper handling of length parameter inconsistency vulnerability in Zlib compressed protocol headers. This vulnerability may allow a read of uninitialized heap memory by an unauthenticated client.
The following remediation steps are recommended / required by January 19, 2026: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vulnerability Analysis
CVE-2025-14847 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors in an automatable fashion. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
What is a length manipulation Vulnerability?
The software parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data. If an attacker can manipulate the length parameter associated with an input such that it is inconsistent with the actual length of the input, this can be leveraged to cause the target application to behave in unexpected, and possibly, malicious ways. One of the possible motives for doing so is to pass in arbitrarily large input to the application. Another possible motivation is the modification of application state by including invalid data for subsequent properties of the application. Such weaknesses commonly lead to attacks such as buffer overflows and execution of arbitrary code.
CVE-2025-14847 has been classified to as a length manipulation vulnerability or weakness.
Products Associated with CVE-2025-14847
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Affected Versions
MongoDB Inc. MongoDB Server:- Version 8.2 and below 8.2.3 is affected.
- Version 8.0 and below 8.0.17 is affected.
- Version 7.0 and below 7.0.28 is affected.
- Version 6.0 and below 6.0.27 is affected.
- Version 5.0 and below 5.0.32 is affected.
- Version 4.4 and below 4.4.30 is affected.
- Version 4.2 is affected.
- Version 4.0 is affected.
- Version 3.6 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.