How severe is CVE-2026-81521?

CVE-2026-81521 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-81521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-81521?

CVE-2026-81521 affects Mongodb Go Driver. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-81521?

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

When was CVE-2026-81521 published?

CVE-2026-81521 was published on 2026-08-27 and last updated on 2026-10-06.

CVE-2026-81521

CVE-2026-81521 is a medium-severity vulnerability in Mongodb Go Driver with a CVSS 3.x base score of 6.5. 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-99.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.1
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-99
Affected product: Mongodb Go Driver
Published: 2026-08-27
Last modified: 2026-10-06

Description

The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.

Frequently asked questions

What is CVE-2026-81521?: The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.
How severe is CVE-2026-81521?: CVE-2026-81521 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-81521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-81521?: CVE-2026-81521 affects Mongodb Go Driver. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-81521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-81521 published?: CVE-2026-81521 was published on 2026-08-27 and last updated on 2026-10-06.

References

Affected products (1)

cpe:2.3:a:mongodb:go_driver:*:*:*:*:*:mongodb:*:*

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