Bug 2451445 (CVE-2026-33219) - CVE-2026-33219 github.com/nats-io/nats-server: NATS-Server: Denial of Service via unbounded memory use in WebSockets
Summary: CVE-2026-33219 github.com/nats-io/nats-server: NATS-Server: Denial of Service...
Keywords:
Status: NEW
Alias: CVE-2026-33219
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2451494
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-03-25 20:02 UTC by OSIDB Bzimport
Modified: 2026-03-25 21:14 UTC (History)
5 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-03-25 20:02:06 UTC 
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.
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