Vulnerability · Published Aug 28, 2026 · Assigned by mongodb
CVE-2026-81520MongoDB Connector for BI Unbounded Authentication Negotiation Leading to Connection Exhaustion
High 7.5
In plain English
A high-severity security flaw in BI Connector from MongoDB. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities).
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| MongoDB | BI Connector | 0 – before 2.14.31 |
Weakness: CWE-1088 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H