CVE-2026-84970
MEDIUMDescription
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 to fix
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 0% of all known CVEs.
References
Related Vulnerabilities
Other CWE-681 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-34169 | High | 7.5 | 81% | - | Fix |
| CVE-2009-0231 | High | 8.8 | 37% | - | - |
| CVE-2016-3074 | Critical | 9.8 | 37% | - | Fix |
| CVE-2008-1721 | High | 7.5 | 23% | - | Fix |
| CVE-2017-7308 | High | 7.8 | 18% | - | Fix |
| CVE-2022-43663 | High | 8.1 | 14% | - | - |
Common questions
How do I fix CVE-2026-84970?
Upgrade mongo-cxx-driver on debian unstable to 4.5.2-1 or later.
Is CVE-2026-84970 being actively exploited?
Not that we know of. CVE-2026-84970 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.09% is the estimated probability that it will be exploited in the next 30 days. That is higher than 0% of all scored CVEs.
How severe is CVE-2026-84970?
CVE-2026-84970 has a CVSS v3 base score of 6.2, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-84970 affect?
Published advisories record a fix for mongo-cxx-driver (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-10.