Allocation of Resources Without Limits or Throttling Affecting github.com/nats-io/nats-server/v2/server package, versions <2.11.15>=2.12.0-RC.1 <2.12.6
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published6 Apr 2026
- disclosed24 Mar 2026
- creditUnknown
Introduced: 24 Mar 2026
CVE-2026-33219 Â (opens in a new tab)How to fix?
Upgrade github.com/nats-io/nats-server/v2/server to version 2.11.15, 2.12.6 or higher.
Overview
github.com/nats-io/nats-server/v2/server is an A simple, secure and performant communications system for digital systems, services and devices.
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling through the checkBytesLimits, tieredReservation, tieredStreamAndReservationCount, and configUpdateCheck functions in the JetStream components. An attacker can bypass storage limit checks and trigger unbounded resource consumption, causing the server to reject legitimate requests or become unavailable by creating or updating streams with extremely large MaxBytes and replica counts, or by sending oversized WebSocket client data before authentication.
Workaround
This vulnerability can be mitigated by disabling the WebSockets client service if it is not required.