CVE-2026-106431

One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver

MEDIUM
5.7
CVSS Score
Published: October 8, 2026 at 06:40 PM UTC
Updated: October 8, 2026 at 08:49 PM UTC
1 product affected across 1 vendorC++ Driver

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Severity
MEDIUM5.7
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

Description

An off-by-one error in the BSON bulk document writer in the MongoDB C Driver can write one zero byte immediately past a heap allocation when a document ends at a specific buffer boundary. An actor who can influence the size of documents serialized by an embedding application can corrupt adjacent process memory or terminate the process. Reaching this issue requires the application to use the BSON bulk-writer API and produce a precise cumulative document size.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

0.5.0 ≤ v < 1.30.132.0.0 ≤ v < 2.5.60.5.02.0.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.7MEDIUMmongodb
Attack Vector
LOCAL
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
HIGH
Vector?

Quick Info

StatusUNDERGOING ANALYSIS
CWE
CWE-787

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