Linuxfoundation: >> Nats-Server Security Vulnerabilities
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 enabled (which it is, by default, when leafnodes are used). Versions 2.11.14 and 2.12.5 contain a fix. As a workaround, disable compression on the leafnode port.
CVSS Score
7.5
EPSS Score
0.001
Published
2026-03-25
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.
CVSS Score
7.5
EPSS Score
0.001
Published
2026-03-25
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.
CVSS Score
6.5
EPSS Score
0.0
Published
2026-03-24
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 consumption of the memory stream when constructing a NATS message which might then fail validation for size reasons. An attacker can use a compression bomb to cause excessive memory consumption, often resulting in the operating system terminating the server process. The use of compression is negotiated before authentication, so this does not require valid NATS credentials to exploit. The fix, present in versions 2.11.2 and 2.12.3, was to bounds the decompression to fail once the message was too large, instead of continuing on. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points.
CVSS Score
5.9
EPSS Score
0.0
Published
2026-02-24
NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. The cryptographic key handling library, nkeys, recently gained support for encryption, not just for signing/authentication. This is used in nats-server 2.10 (Sep 2023) and newer for authentication callouts. In nkeys versions 0.4.0 through 0.4.5, corresponding with NATS server versions 2.10.0 through 2.10.3, the nkeys library's `xkeys` encryption handling logic mistakenly passed an array by value into an internal function, where the function mutated that buffer to populate the encryption key to use. As a result, all encryption was actually to an all-zeros key. This affects encryption only, not signing.
FIXME: FILL IN IMPACT ON NATS-SERVER AUTH CALLOUT SECURITY. nkeys Go library 0.4.6, corresponding with NATS Server 2.10.4, has a patch for this issue. No known workarounds are available. For any application handling auth callouts in Go, if using the nkeys library, update the dependency, recompile and deploy that in lockstep.
CVSS Score
7.5
EPSS Score
0.001
Published
2023-10-31
NATS nats-server before 2.9.23 and 2.10.x before 2.10.2 has an authentication bypass. An implicit $G user in an authorization block can sometimes be used for unauthenticated access, even when the intention of the configuration was for each user to have an account. The earliest affected version is 2.2.0.
CVSS Score
6.5
EPSS Score
0.003
Published
2023-10-30
NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action from a management account.
CVSS Score
9.8
EPSS Score
0.002
Published
2023-09-19
NATS nats-server before 2.7.4 allows Directory Traversal (with write access) via an element in a ZIP archive for JetStream streams. nats-streaming-server before 0.24.3 is also affected.
CVSS Score
6.5
EPSS Score
0.007
Published
2022-03-10
NATS nats-server before 2.7.2 has Incorrect Access Control. Any authenticated user can obtain the privileges of the System account by misusing the "dynamically provisioned sandbox accounts" feature.
CVSS Score
8.8
EPSS Score
0.007
Published
2022-02-08
NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.
CVSS Score
7.5
EPSS Score
0.003
Published
2021-03-16