6.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2021-20329

CVE-2021-20329: go.mongodb.org/mongo-driver improperly validates cstrings when marshalling Go objects into BSON

Specific cstrings input may not be properly validated in the MongoDB Go Driver when marshalling Go objects into BSON. A malicious user could use a Go object with specific string to potentially inject additional fields into marshalled documents. This issue affects all MongoDB GO Drivers up to (and including) 1.5.0.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2021-20329

CVE-2021-20329:

6.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
go.mongodb.org/mongo-driver	go	< 1.5.1	1.5.1

Technical Details

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Root Cause Analysis

The commit 2aca31d5986a9e1c65a92264736de9fdc3b9b4ca introduces validation checks for null bytes in BSON key names and regex fields, addressing CVE-2021-20329. The functions modified in this commit (WriteRegex, writeElementHeader, AppendHeader, AppendRegex) are directly involved in processing user-provided data during BSON marshalling. The added checks indicate that these functions previously lacked proper input validation, allowing attackers to inject null bytes and manipulate the resulting BSON structure. These functions would appear in stack traces or runtime profiles when processing malicious payloads, as they are entry points for BSON serialization where the vulnerability could be triggered.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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