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CVE-2026-84970

medium

A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library.

Vendor / product: Mongodb — c\+\+ driver

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.

CVSS
5.8
5.8 (CVSS v3.1)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-09-03 15:17
Modified: 2026-09-10 19:47
NVD status: Analyzed
Last synced 1 day ago
Verified against the source API 2026-10-27 06:50 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mongodb / c\+\+_driver ≥3.2.0 <4.5.2

Weakness classification (CWE)

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://jira.mongodb.org/browse/CXX-3547

References

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:50 UTC · record ↗

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