5.3mediumMedium
CVE-2026-33219
Linuxfoundation Nats-Server
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.
Exploitation status
- A vendor advisory or patch reference has been published.
What the metrics mean
- It is reachable over a network, without needing local access.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, no account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 5.3 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness
- CWE-770
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-03-25
- Last modified
- 2026-08-24
- Sources
- NVD
Affected products
- Linuxfoundation Nats-Server- 2.11.15, 2.12.0 - 2.12.6
As listed in the NVD configuration data. Not a statement about your estate.
References
- https://advisories.nats.io/CVE/secnote-2026-02.txt
- https://advisories.nats.io/CVE/secnote-2026-11.txt
- https://github.com/advisories/GHSA-qrvq-68c2-7grw
- https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j
- https://access.redhat.com/errata/RHSA-2026:21769
- https://access.redhat.com/errata/RHSA-2026:22347
- https://access.redhat.com/errata/RHSA-2026:23345
- https://access.redhat.com/security/cve/CVE-2026-33219
- https://bugzilla.redhat.com/show_bug.cgi?id=2451445
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33219.json