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How the mentioned CVE works:
The vulnerability stems from inconsistent object size validation within MongoDB’s time series processing logic. When BSON documents are handled in time series collections, initial validation stages may fail to properly enforce size limits. This allows oversized BSON documents to pass through early checks. Later, during further processing, an assert statement triggers to verify document size consistency. Since the document exceeds expected limits, the assert fails, leading to a fatal error and immediate termination of the MongoDB server process. This results in a denial of service condition. The issue specifically affects time series data handling, where document size validation is not uniform across the processing pipeline. Versions impacted include v7.0 before 7.0.26, v8.0 before 8.0.16, and v8.2 before 8.2.1. The crash occurs without warning, disrupting database availability.
Platform: MongoDB Server
Version: v7.0, v8.0, v8.2
Vulnerability: Inconsistent size validation
Severity: Critical
Date: 11/25/2025
Prediction: Patches available now
What Undercode Say:
Analytics:
- Check version: `db.version()`
– Time series creation: `db.createCollection(“ts”, { timeseries: { timeField: “time” } })`
– Update package: `sudo apt-get upgrade mongodb-org`
how Exploit:
Insert oversized BSON documents into time series collections via malicious insert operations, bypassing initial validation to trigger assert failure and crash.
Protection from this CVE
Update to versions 7.0.26, 8.0.16, or 8.2.1; implement strict BSON size validation in time series processing.
Impact:
Denial of service through server termination, affecting database availability.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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