CVE-2026-84970

CVE-2026-84970 is a medium-severity vulnerability in Mongodb C++ Driver with a CVSS 3.x base score of 6.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-681.

Key facts

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.

Frequently asked questions

What is CVE-2026-84970?
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.
How severe is CVE-2026-84970?
CVE-2026-84970 has a CVSS 3.x base score of 6.2, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2026-84970 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-84970?
CVE-2026-84970 affects Mongodb C++ Driver. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-84970?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-84970 published?
CVE-2026-84970 was published on 2026-09-03 and last updated on 2026-09-10.

References

Affected products (1)

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