Nats-Io Nats-Server vulnerabilities

CVE-2025-30215 [CRITICAL] CWE-287 CVE-2025-30215: NATS-Server is a High-Performance server for NATS.io, the cloud and edge native messaging system. In NATS-Server is a High-Performance server for NATS.io, the cloud and edge native messaging system. In versions starting from 2.2.0 but prior to 2.10.27 and 2.11.1, the management of JetStream assets happens with messages in the $JS. subject namespace in the system account; this is partially exposed into regular accounts to allow account holders to

CVE-2026-58253 [HIGH] CWE-287 CVE-2026-58253: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentica

CVE-2026-58250 [HIGH] CWE-476 CVE-2026-58250: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.12.8 and 2.11.17, an unauthenticated peer with network access to a leafnode listener with compression enabled could crash the server during the pre-authentication leafnode handshake by sending repeated leafnode INFO protocol messages before aut

CVE-2026-27889 [HIGH] CWE-190 CVE-2026-27889: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Star 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 websocke

CVE-2026-58210 [HIGH] CWE-400 CVE-2026-58210: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an unauthenticated MQTT client could cause the server to retain large incomplete MQTT CONNECT packets before authentication completed, consuming server memory while the parser waited for the advertised MQTT packet length. This

CVE-2026-58208 [HIGH] CWE-248 CVE-2026-58208: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with access to the WebSocket listener to reach uninitialized M

CVE-2026-33216 [HIGH] CWE-256 CVE-2026-33216: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio 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, for MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints. Versions 2.11.14 and 2.12.6 contain a fix.

CVE-2026-29785 [HIGH] CWE-476 CVE-2026-29785: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.14 and 2.12.5, if the nats-server has the "leafnode" configuration enabled (not default), then anyone who can connect can crash the nats-server by triggering a panic. This happens pre-authentication and requires that compression be en

CVE-2026-33218 [HIGH] CWE-20 CVE-2026-33218: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio 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 client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable leafnode support if not n

CVE-2026-27571 [HIGH] CWE-409 CVE-2026-27571: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The WebSockets handling of NATS messages handles compressed messages via the WebSockets negotiated compression. Prior to versions 2.11.2 and 2.12.3, the implementation bound the memory size of a NATS message but did not independently bound the memory consump

CVE-2026-58213 [HIGH] CWE-74 CVE-2026-58213: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.1 and 2.12.9, an MQTT client could include protocol control characters in subscription filters that were later forwarded as NATS protocol data to route or leafnode connections, corrupting the forwarded protocol stream and allowing injection o

CVE-2026-58251 [MEDIUM] CWE-285 CVE-2026-58251: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user with subscription deny permissions could bypass a plain subject deny rule by using a queue subscription, because queue-specific deny evaluation could override the plain subject deny result when

CVE-2026-58252 [MEDIUM] CWE-285 CVE-2026-58252: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user could receive messages on denied subjects when a wildcard subscription overlapped with a configured wildcard deny rule but was not a subset of it, and queue subscriptions could also affect deli

CVE-2026-58207 [MEDIUM] CWE-190 CVE-2026-58207: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a client able to send account-scoped connection monitoring requests could crash the server by supplying Connz pagination Offset and Limit values that overflowed internal arithmetic before the response window was safely bound

CVE-2026-33217 [MEDIUM] CWE-863 CVE-2026-33217: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio 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, when using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects. Versions 2.11.15 and 2.12.6 contain a fix. No known workaround

CVE-2026-33215 [MEDIUM] CWE-287 CVE-2026-33215: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server provides an MQTT client interface. Prior to versions 2.11.15 and 2.12.5, Sessions and Messages can by hijacked via MQTT Client ID malfeasance. Versions 2.11.15 and 2.12.5 patch the issue. No known workarounds are available.

CVE-2026-33247 [MEDIUM] CWE-215 CVE-2026-33247: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio 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, if a nats-server is run with static credentials for all clients provided via argv (the command-line), then those credentials are visible to any user who can see the monitoring port, if that too is enabled. The `/debug

CVE-2026-58211 [MEDIUM] CWE-863 CVE-2026-58211: NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Pr NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a client could be registered as the configured no_auth_user through a parser path used when the first client operation was not CONNECT, bypassing user-level connection restrictions such as allowed_connection_types or proxy_r

CVE-2026-33223 [MEDIUM] CWE-290 CVE-2026-33223: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prio 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, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credent

CVE-2026-33246 [MEDIUM] CWE-287 CVE-2026-33246: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to tr