Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer() (CVE-2026-93395) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-93395

Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer()

Answer in brief

CVE-2026-93395 records a Unknown severity vulnerability in Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer(). The current sources do not mark it as known exploited. The current feed maps MongoDB Inc./C Driver (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps MongoDB Inc./C Driver (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
MongoDB Inc./C Drivergeneric	>=2.0.0 <2.3.1	2.3.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for MongoDB Inc./C Driver.
Review the reported fix. Update MongoDB Inc./C Driver to 2.3.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Source referencejira.mongodb.org

Upstream source description

A missing lower-bound validation in the bson_new_from_buffer() function of libbson allows an integer underflow when processing BSON data with a zero-length prefix. The function reads a 32-bit document length from the input buffer but does not verify that the value is at least 5 (the minimum valid BSON document size) before using it in an array index calculation. When the length field is zero, the expression used to check the document's null terminator wraps to UINT32_MAX, causing a heap out-of-bounds read that crashes the process. An unauthorized party who can supply crafted BSON input to an application using this API can cause a denial of service.

Quoted source text, attributed separately from HOL analysis.