Unbounded mem growth via MongoDB C Driver compressed responses CVE-2026-120678
CVE-2026-120678 Published on November 3, 2026
MongoDB C Driver leaks the decompressed reply buffer when an OP_COMPRESSED reply fails to parse (denial of service)
A memory management flaw in the MongoDB C Driver's handling of compressed responses may cause the client library to hold on to memory that is never released. An unauthenticated party that controls the database endpoint a client application connects to may cause repeated, unbounded memory growth in that application, which may result in the application becoming unavailable. No credentials, transport security settings, or user interaction are required.
Vulnerability Analysis
CVE-2026-120678 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is a Memory Leak Vulnerability?
The software does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is often triggered by improper handling of malformed data or unexpectedly interrupted sessions. In some languages, developers are responsible for tracking memory allocation and releasing the memory. If there are no more pointers or references to the memory, then it can no longer be tracked and identified for release.
CVE-2026-120678 has been classified to as a Memory Leak vulnerability or weakness.
Products Associated with CVE-2026-120678
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Affected Versions
MongoDB C Driver:- Version 1.25.0, <= 1.30.14 is affected.
- Version 2.0.0, <= 2.5.7 is affected.