How severe is CVE-2026-84965?

CVE-2026-84965 has a CVSS 3.x base score of 5.1, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-84965 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-84965?

CVE-2026-84965 affects Mongodb C Driver. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-84965?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-84965 published?

CVE-2026-84965 was published on 2026-09-03 and last updated on 2026-09-22.

CVE-2026-84965

CVE-2026-84965 is a medium-severity vulnerability in Mongodb C Driver with a CVSS 3.x base score of 5.1. 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-190.

Key facts

Severity: Medium (CVSS 3.x base score 5.1)
CVSS v4: 5.9
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Mongodb C Driver
Published: 2026-09-03
Last modified: 2026-09-22

Description

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.

Frequently asked questions

What is CVE-2026-84965?: An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.
How severe is CVE-2026-84965?: CVE-2026-84965 has a CVSS 3.x base score of 5.1, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-84965 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-84965?: CVE-2026-84965 affects Mongodb C Driver. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-84965?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-84965 published?: CVE-2026-84965 was published on 2026-09-03 and last updated on 2026-09-22.

References

https://jira.mongodb.org/browse/CDRIVER-6405

Affected products (1)

cpe:2.3:a:mongodb:c_driver:*:*:*:*:*:mongodb:*:*

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