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CVE-2026-58253— NATS Server: Route API Auth Bypass

Quick assessment

Affected
nats-io nats-server
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NATS Server是Nats团队开源的一个云原生消息系统。 NATS Server存在授权问题漏洞，该漏洞源于当配置了no_auth_user时，用于普通客户端连接的解析器快速路径也可能应用于路由或叶节点监听器，导致未经身份验证的节点可以绕过服务器间CONNECT身份验证并以该连接类型的权限进行操作。以下版本受到影响：2.11.16之前版本和2.12.0-preview.1至2.12.6之前版本。

CVSS 8.8 · High EPSS 0.37% · P29

Possible ATT&CK Techniques 1 AI

T1199 · Trusted Relationship

Affected Version Matrix 2

VendorProduct Version RangeStatus
nats-io nats-server < 2.11.16 affected
>= 2.12.0-preview.1, < 2.12.6 affected
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I. Basic Information for CVE-2026-58253

Vulnerability Information
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Vulnerability Title
NATS Server: Route API Auth Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
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 authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
NATS Server 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
NATS Server是Nats团队开源的一个云原生消息系统。 NATS Server存在授权问题漏洞，该漏洞源于当配置了no_auth_user时，用于普通客户端连接的解析器快速路径也可能应用于路由或叶节点监听器，导致未经身份验证的节点可以绕过服务器间CONNECT身份验证并以该连接类型的权限进行操作。以下版本受到影响：2.11.16之前版本和2.12.0-preview.1至2.12.6之前版本。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
nats-io nats-server < 2.11.16 -

II. Public POCs for CVE-2026-58253

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 8382 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-58253

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Patches & Fixes for CVE-2026-58253 (3)

Vendor Advisories for CVE-2026-58253 (1)

Vendor Pages for CVE-2026-58253 (2)

Same Patch Batch · nats-io · 2026-07-08 · 12 CVEs total

CVE-2026-58207 7.7 HIGH NATS Server: Remote crash via integer overflow in Connz pagination
CVE-2026-58250 7.5 HIGH NATS Server: Pre-auth server crash via double INFO in leafnode handshake
CVE-2026-58210 7.5 HIGH NATS Server: MQTT partial CONNECT packets can exhaust pre-auth memory
CVE-2026-58213 7.1 HIGH NATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbit
CVE-2026-58208 6.8 MEDIUM NATS Server: MQTT-over-WebSocket Path Can Crash WebSocket-Only JetStream Servers Before MQ
CVE-2026-58251 6.5 MEDIUM NATS Server: Queue Subscribe Authz Bypass
CVE-2026-58252 6.5 MEDIUM NATS Server: Subscribe Authz Bypass via Wildcard-Overlap
CVE-2026-58211 5.4 MEDIUM NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
CVE-2026-58214 4.3 MEDIUM NATS Server: MQTT subscribe ACL bypass via $MQTT.deliver.pubrel prefix (incomplete fix for
CVE-2026-58209 4.3 MEDIUM NATS Server: MQTT retained and QoS replay bypass subscribe deny filters
CVE-2026-58254 NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-De

IV. Related Vulnerabilities

Same product: nats-server
Same vendor: nats-io
Same weakness: CWE-287

V. Comments for CVE-2026-58253

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