CVE-2026-84969

Analyzed Analyzed - Analysis Complete

Memory Corruption in MongoDB C Driver BSON Conversion

Publication date: 2026-09-03

Last updated on: 2026-09-10

Assigner: MongoDB, Inc.

Description

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-03

Last Modified

2026-09-10

Generated

2026-09-23

AI Q&A

2026-09-03

EPSS Evaluated

2026-09-22

NVD

CVE-2026-84969

EUVD

EUVD-2026-70508

Affected Vendors & Products

Vendor	Product	Version / Range
mongodb	c_driver	From 2.0.0 (inc) to 2.5.2 (exc)
mongodb	c_driver	From 1.30.0 (inc) to 1.30.9 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-787	The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This vulnerability is a memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver. It occurs when a binary field is encoded and the output is cut short at a caller-configured length limit, causing a small number of bytes to be written past the end of a heap buffer. This can lead to unintended data alteration outside the intended buffer.

Detection Guidance

This vulnerability involves a memory-handling error in the MongoDB C Driver's BSON-to-JSON conversion. Detection requires checking for affected versions of the MongoDB C Driver and monitoring for unusual memory writes or crashes during BSON processing. No specific commands are provided in the context.

Impact Analysis

An attacker who supplies document content without privileges on the application using the MongoDB C Driver could cause minor data corruption or unintended memory changes. This may lead to application instability or unexpected behavior, but the impact is limited due to the small amount of data affected.

Compliance Impact

This vulnerability may pose minor compliance risks if it leads to unintended data corruption or exposure. However, the limited scope of memory alteration and lack of direct data exfiltration suggest minimal impact on GDPR or HIPAA compliance. Organizations should still assess their specific use cases.

Mitigation Strategies

Update the MongoDB C Driver to the latest patched version to address the memory-handling error in BSON-to-JSON conversion.

Hi! I’m here to help you understand CVE-2026-84969. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70