CVE-2026-84966

BSON element injection via NUL-embedded document keys in builder append

Published Sep 3, 2026 CVSS 4.0 · 5.9 Medium EPSS < 1% KEV · Not listed
Description
An incorrect numeric type conversion in the BSON document building component of the MongoDB C++ Driver may cause a length value to be interpreted incorrectly. When an application supplies an extremely large, non-terminated field name to the builder, the library may read memory outside the intended buffer and terminate the calling process. No authentication is required, but the calling application must pass the oversized name in a specific form.

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
Metrics ssvc

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

Type Values Removed Values Added
First Time appeared Mongodb
Mongodb c++ Driver
Vendors & Products Mongodb
Mongodb c++ Driver
Type Values Removed Values Added
Description An incorrect numeric type conversion in the BSON document building component of the MongoDB C++ Driver may cause a length value to be interpreted incorrectly. When an application supplies an extremely large, non-terminated field name to the builder, the library may read memory outside the intended buffer and terminate the calling process. No authentication is required, but the calling application must pass the oversized name in a specific form.
Title BSON element injection via NUL-embedded document keys in builder append
Weaknesses CWE-681
References
Metrics cvssV3_1

{'score': 5.1, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
mongodb
Published
Updated
Sep 3, 2026, 3:38 PM
Reserved
Sep 2, 2026, 5:58 PM
Status
Analyzed
Published
Sep 3, 2026, 4:18 PM
Modified
Sep 22, 2026, 3:54 PM