Nats Server

Insufficient data exists to characterize this vulnerability. CVE-2026-58214 was reported by Ubuntu (vendor source) but carries no description, CVSS score, vector, or CWE at time of analysis. The affected component, attack vector, and impact are all unknown. Security teams should monitor the Ubuntu Security Notices (USN) feed and the NVD entry for this CVE for forthcoming details.

Denial of service in NATS Server (nats-io/nats-server) affects the HTTP monitoring endpoints /connz and /subsz, where attacker-controlled offset and limit pagination parameters trigger a signed integer overflow (Offset+Limit wrapping from math.MaxInt64 to math.MinInt64), producing invalid slice bounds and a server panic. Any client able to reach the monitoring interface can crash the broker, disrupting all connected messaging clients. There is no public exploit identified at time of analysis and the issue is not in CISA KEV; the upstream fix clamps offsets using min/max bounds.

Remote denial-of-service in NATS Server (nats-server) affects deployments with the WebSocket listener enabled but MQTT disabled; per the GHSA-p957-7v2w-g93g advisory and the fixing commit, an unauthenticated attacker can send an MQTT-over-WebSocket upgrade request to the WebSocket endpoint while MQTT is turned off, triggering an uncaught exception (CWE-248) that crashes the server (CVSS 7.5, availability-only impact). This is a Linux Foundation CNCF messaging component fixed in nats-server 2.12.12 and 2.14.3. No public exploit identified at time of analysis; not listed in CISA KEV, and EPSS is low at 0.53% (41st percentile), consistent with the SSVC assessment of exploitation 'none' and only partial technical impact.

Insufficient data exists to characterize CVE-2026-58209 beyond its association with an Ubuntu vendor report. The CVE description is absent, no CVSS score or vector has been assigned, no CWE root cause is identified, and no additional intelligence sources were provided. Security teams should treat this as an unresolved reservation requiring active follow-up with Ubuntu Security Notices (USN) or the NVD pending full disclosure.

Denial of service in NATS Server (nats-server) MQTT handler allows a remote, unauthenticated client to exhaust server memory by sending an MQTT CONNECT packet that declares a large variable-length 'remaining length' before authentication completes. Because the pre-connection MQTT parser failed to enforce the configured max_payload limit, the server would buffer attacker-controlled data unbounded, degrading or crashing the broker (CVSS 7.5, availability-only impact). There is no public exploit identified at time of analysis and it is not listed in CISA KEV, but the fix is confirmed by upstream commits, releases, and a GitHub Security Advisory.

CVE-2026-58211 was reported by Ubuntu with no description, CVSS score, CWE, or technical detail available at time of analysis. The affected product, vulnerability class, and impact cannot be determined from available data. Security teams should monitor the Ubuntu security tracker and NVD for updates before assessing risk.

Protocol injection in NATS Server MQTT support allows an authenticated MQTT client to smuggle control characters (tab, newline, carriage return, form feed) inside publish and Will topics, which corrupt the NATS wire protocol when the topic is converted to a NATS subject and forwarded across leaf node connections. Fixed in nats-server v2.12.9 and v2.14.1, the flaw (GHSA-qrcv-3558-gj4f, CWE-74) is tagged Information Disclosure and lets a low-privileged publisher influence how messages are framed and routed to other connections. No public exploit identified at time of analysis and it is not listed in CISA KEV.

CVE-2026-58254 has been reported through Ubuntu's vendor channel, but no description, CVSS score, CWE classification, or technical details are available in the provided intelligence data. The affected product, vulnerability class, and impact cannot be characterized at this time. No meaningful synthesis is possible without a description, patch reference, or advisory content.

Authentication bypass in NATS Server (nats-io/nats-server) lets an unauthenticated attacker on an adjacent network connect to the cluster (route) or leafnode listener and be silently dropped into the privileged no_auth_user account, bypassing the separate route/leafnode authorization. Any server configured with no_auth_user is affected up to the fixed releases (v2.11.16, v2.12.7, v2.14.0), enabling cross-account message injection over the internal route protocol. No public exploit identified at time of analysis, though the vendor's own regression test demonstrates the exact attack.

CVE-2026-58252 is attributed to Ubuntu per vendor reporting, but no description, CVSS score, CWE classification, or technical details are available in the provided intelligence data. The vulnerability cannot be characterized beyond its association with the Ubuntu platform. Security teams should consult Ubuntu Security Notices (USN) directly for authoritative details as this record is effectively unpopulated.

CVE-2026-58251 has been reported by Ubuntu with no description, CVSS score, CWE classification, or technical details available at time of analysis. The affected component, attack vector, and impact are entirely unknown. No exploitation status, patch availability, or severity rating can be determined from the provided intelligence.

Remote denial of service in the NATS Server (nats-io/nats-server) leafnode subsystem allows unauthenticated attackers to crash the entire server by sending a second INFO protocol message before CONNECT on the leafnode port, triggering a nil-pointer dereference (c.acc == nil) that panics the process. All server instances exposing a leafnode listener prior to v2.11.17 (2.11.x) and v2.12.8 (2.12.x) are affected. No public exploit has been identified, but the vendor's own regression test (TestLeafNodeSecondInfoBeforeConnectDoesNotPanic) demonstrates the exact crash payload, and the CVSS availability-only vector (7.5) reflects a single-packet, no-auth crash.

NATS Server versions prior to 2.11.2 and 2.12.3 fail to properly limit memory allocation during WebSocket compression, allowing unauthenticated attackers to trigger denial of service through compression bomb attacks that exhaust server memory. The vulnerability is exploitable pre-authentication since compression negotiation occurs before credential validation. A patch is available in versions 2.11.2 and 2.12.3.

NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

NATS nats-server before 2.9.23 and 2.10.x before 2.10.2 has an authentication bypass. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

NATS nats-server before 2.7.4 allows Directory Traversal (with write access) via an element in a ZIP archive for JetStream streams. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. This Path Traversal vulnerability could allow attackers to access files and directories outside the intended path.

NATS nats-server before 2.7.2 has Incorrect Access Control. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. This Missing Authorization vulnerability could allow attackers to access resources or perform actions without proper authorization checks.

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. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

This affects all versions of package github.com/nats-io/nats-server/server. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are handled. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use of Hard-coded Credentials vulnerability could allow attackers to gain access using credentials embedded in source code.

The JWT library in NATS nats-server before 2.1.9 allows a denial of service (a nil dereference in Go code). Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.

An integer overflow in NATS Server before 2.0.2 allows a remote attacker to crash the server by sending a crafted request. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.