# CVE-2026-81520: MongoDB Connector for BI denial of service via incomplete SASL authentication

Source: https://junglewise.ai/threats/cve-2026-81520-mongodb-connector-for-bi-denial-of-service-via-incomplete-sasl  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-28. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-81520 · Severity: high · CVSS 7.5 · Published 2026-08-28

MongoDB Connector for BI is a tool that bridges MongoDB databases to business intelligence platforms. An unauthenticated attacker on the network can indefinitely hold open authentication sessions by starting but never completing the login process, consuming server resources and preventing legitimate users from connecting to the system.

Technologies: [MongoDB Connector for BI](https://junglewise.ai/threats/technologies/connector-for-bi). Vendors: [MongoDB](https://junglewise.ai/threats/vendors/mongodb).

## Quick answers

**Is CVE-2026-81520 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81520 being exploited in the wild.

**How severe is CVE-2026-81520?** High severity, with a CVSS score of 7.5, published 28 August 2026.

**Which products and versions are affected?** MongoDB Connector for BI.

**Is there a fix for CVE-2026-81520?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-81520 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-81520?** Check whether you run MongoDB Connector for BI. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a denial-of-service vulnerability in MongoDB Connector for BI's SASL authentication handler. An unauthenticated client on the network can initiate a SASL login exchange and then deliberately not complete it, causing the server to hold the connection indefinitely. The root cause is the absence of a timeout on the overall negotiation loop and no read deadline on client communications. Each incomplete session occupies a worker thread, client connection slot, and associated backend database connections. By repeated exploitation, an attacker can exhaust the configured connection pool and prevent legitimate users from establishing sessions. Patches are available in updated release notes documented by MongoDB.

## Affected products

- MongoDB Connector for BI

## Timeline

- 2026-08-28: published
- 2026-08-28: disclosed

## References

- [https://www.mongodb.com/docs/bi-connector/current/release-notes/](https://www.mongodb.com/docs/bi-connector/current/release-notes/)

## Related threats

- [MongoDB Connector for BI client certificate validation bypass](https://junglewise.ai/threats/cve-2026-81518-mongodb-connector-for-bi-client-certificate-validation-bypass)
- [MongoDB Connector for BI denial of service via log exhaustion](https://junglewise.ai/threats/cve-2026-81517-mongodb-connector-for-bi-denial-of-service-via-log-exhaustion)
- [MongoDB Connector for BI schema-sampling denial of service](https://junglewise.ai/threats/cve-2026-81490-mongodb-connector-for-bi-schema-sampling-denial-of-service)
- [MongoDB Connector for BI SQL injection via unescaped identifiers](https://junglewise.ai/threats/cve-2026-77586-mongodb-connector-for-bi-sql-injection-via-unescaped-identifiers)
- [MongoDB Connector for BI SQL injection in JSON schema validator comments](https://junglewise.ai/threats/cve-2026-77184-mongodb-connector-for-bi-sql-injection-in-json-schema-validator)