VYPR
High severityNVD Advisory· Published Mar 25, 2026· Updated Mar 25, 2026

NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead

CVE-2026-27889

Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
github.com/nats-io/nats-server/v2Go
>= 2.2.0, < 2.11.142.11.14
github.com/nats-io/nats-server/v2Go
>= 2.12.0, < 2.12.52.12.5
github.com/nats-io/nats-serverGo
>= 0

Affected products

1

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

4

News mentions

0

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