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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 c…

Medium CVSS 5.3
CVECVE-2026-33219
First seen2026-07-20 13:16 UTC
Disclosed2026-03-25 20:16 UTC
Last updated2026-07-20 13:16 UTC
Channel statusauto

Summary

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 b…

In-depth triage · Auto channel

No in-depth report has been generated yet (DR-003 v2 AI pipeline is under construction).

Affected products

  • :
Lint boundary warnings (2)

The following non-blocking warnings were raised during the lint phase of this triage (e.g. reference URLs not yet on the allowlist). They do not affect entry usability and are disclosed for transparency (see DR-002).

  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://advisories.nats.io/CVE/secnote-2026-02.txt
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://advisories.nats.io/CVE/secnote-2026-11.txt

Sources

  • NVD DATABASE

Original Links

Timeline

  1. nvd_ingest NVD