CVE-2026-81520 MongoDB Connector for BI Unbounded Authentication Negotiation Leading to Connection Exhaustion
Unauthenticated attackers can exhaust connection resources by holding SASL authentication sessions open indefinitely, preventing legitimate users from connecting.
- 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-2026-81520?
CVE-2026-81520 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
A network-reachable client that has not yet authenticated can hold a MongoDB Connector for BI authentication session open indefinitely by beginning a SASL-based login exchange and then declining to complete it. Because the negotiation loop had no overall time bound and the read from the client had no deadline, each such session retains a worker, a client connection slot, and its associated backend database connections until the process is restarted. Repeated use of this behavior can consume the configured connection capacity and prevent legitimate users from establishing new sessions.
Weakness: CWE-1088
Which versions are affected by CVE-2026-81520?
It affects 1 product.
Products include Mongodb Bi Connector.
How do I fix CVE-2026-81520?
No fix has been published for CVE-2026-81520 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-2026-81520 being exploited?
There is no known exploitation of CVE-2026-81520 in the wild and no public exploit code.
Other vulnerabilities in MongoDB BI Connector
- CVE-2026-81517 MongoDB Connector for BI Improper Error Handling of Log Write Failures May Cause Loss of SQL Service
- CVE-2026-81518 BI Connector Optional Client Certificate Verification Allows Unauthenticated Connections
- CVE-2026-77586 MongoDB Connector for BI Unescaped Object Names in Generated SHOW CREATE Output
- CVE-2026-81490 MongoDB Connector for BI Improper Error Handling During Schema Sampling May Cause Loss of SQL Service
- CVE-2026-75159 MongoDB BI Connector Improper Memory Handling During Failed Kerberos Authentication May Cause Process Termination
Sources
Also known as GHSA-435g-jwv8-462q.