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    CVE-2026-33219

    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.

    Published:Mar 25, 2026
    Last Modified:Mar 27, 2026
    EPS:Mar 25, 2026
    EPSS Score:0.00059
    CVSS Score:5.3

    Affected Products

    Vendor
    Linuxfoundation
    Product
    Nats-server
    Vendor
    Nats
    Product
    Nats Server

    Exploits

    No exploit reference

    Related CVEs

    CVE-2026-33249 (CVSS 4.3) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in ve…
    CVE-2026-33223 (CVSS 6.4) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33248 (CVSS 4.2) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33222 (CVSS 4.9) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33247 (CVSS 7.4) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33218 (CVSS 7.5) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33246 (CVSS 6.4) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-serve…
    CVE-2026-33217 (CVSS 7.1) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-33216 (CVSS 8.6) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…
    CVE-2026-29785 (CVSS 7.5) — NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versi…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High