CVE-2026-84970

Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser

Published Sep 3, 2026 CVSS 4.0 · 5.9 Medium EPSS < 1% KEV · Not listed
Description
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Mongodb c\+\+ Driver
CPEs cpe:2.3:a:mongodb:c\+\+_driver:*:*:*:*:*:mongodb:*:*
Vendors & Products Mongodb c\+\+ Driver
Type Values Removed Values Added
First Time appeared Mongodb
Mongodb c\# Driver
Vendors & Products Mongodb
Mongodb c\# Driver
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
Title Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
Weaknesses CWE-681
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H'}

cvssV4_0

{'score': 5.9, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mongodb
Published
Updated
Sep 3, 2026, 3:17 PM
Reserved
Sep 2, 2026, 5:58 PM
Status
Analyzed
Published
Sep 3, 2026, 3:17 PM
Modified
Sep 10, 2026, 7:47 PM