CVE-2026-81517 MongoDB Connector for BI Improper Error Handling of Log Write Failures May Cause Loss of SQL Service

High 8.7 Published 28 Aug 2026 Updated 31 Aug 2026

An unauthenticated attacker can exhaust log storage to crash the MongoDB BI Connector, causing a denial of service for all SQL clients.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-81517?

CVE-2026-81517 is a high-severity denial of service vulnerability in MongoDB BI Connector, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An unauthenticated party able to reach the port of a MongoDB Connector for BI (mongosqld) instance may generate enough routine connection log activity to exhaust the storage backing the configured log path. When a log write or log rotation operation subsequently fails, the resulting error is not handled and the shared mongosqld process ends, ending service for all connected SQL clients. The process continues to end on startup until an operator restores available storage, and the diagnostic message explaining the condition is not recorded.

Weakness: CWE-248

Which versions are affected by CVE-2026-81517?

It affects 1 product.

Products include Mongodb Bi Connector.

How do I fix CVE-2026-81517?

No fix has been published for CVE-2026-81517 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-81517 being exploited?

There is no known exploitation of CVE-2026-81517 in the wild and no public exploit code.

Sources

Also known as GHSA-87fw-525c-9h5m.