CVE-2026-81521 (CVSS 6.5)

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.

Is your site exposed to CVE-2026-81521?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-99 CWE-99

References

Other References

https://jira.mongodb.org/browse/GODRIVER-4075 https://pkg.go.dev/go.mongodb.org/mongo-driver/[email protected]

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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-81521? +

CVE-2026-81521 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-81521? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-43491 9.8

A vulnerability in the Poly Lens Desktop application running on the Windows platform might allow modifications to the filesystem, which …

CVE-2025-0756 9.1

Overview The product receives input from an upstream component, but it does not restrict or incorrectly restricts the input before …

CVE-2024-57971 9.1

DataSourceResource.java in the SpagoBI API support in Knowage Server in KNOWAGE before 8.1.30 does not ensure that java:comp/env/jdbc/ occurs at …

CVE-2025-2410 9.1

Port manipulation vulnerabilities in ASPECT provide attackers with the ability to con-trol TCP/IP port access if session administrator credentials become …

CVE-2024-5706 8.8

The product receives input from an upstream component, but it does not restrict or incorrectly restricts the input before it …

CVE-2023-6605 7.2

A flaw was found in FFmpeg's DASH playlist support. This vulnerability allows arbitrary HTTP GET requests to be made on …

CVE-2026-81521