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CVE-2026-27889— NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead

CVSS 7.5 · High EPSS 0.09% · P25
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I. Basic Information for CVE-2026-27889

Vulnerability Information
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Vulnerability Title
NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead
Source: NVD (National Vulnerability Database)
Vulnerability Description
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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
整数溢出或超界折返
Source: NVD (National Vulnerability Database)
Vulnerability Title
Nats-Server 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Nats-Server是Nats开源的一个用于 Nats.io、云和边缘本机消息传递系统的高性能服务器。 Nats-Server 2.11.14之前版本和2.12.5之前版本存在输入验证错误漏洞，该漏洞源于WebSockets帧缺少完整性检查，可能触发服务器内核崩溃。
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

VendorProductAffected VersionsCPESubscribe
nats-ionats-server >= 2.2.0, < 2.11.14 -

II. Public POCs for CVE-2026-27889

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III. Intelligence Information for CVE-2026-27889

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Same Patch Batch · nats-io · 2026-03-25 · 12 CVEs total

CVE-2026-332168.6 HIGHNATS has MQTT plaintext password disclosure
CVE-2026-297857.5 HIGHNATS Server panic via malicious compression on leafnode port
CVE-2026-332187.5 HIGHNATS has pre-auth server panic via leafnode handling
CVE-2026-332477.4 HIGHNATS credentials are exposed in monitoring port via command-line argv
CVE-2026-332177.1 HIGHNATS allows MQTT clients to bypass ACL checks
CVE-2026-332466.4 MEDIUMNATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers
CVE-2026-332236.4 MEDIUMNATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing
CVE-2026-332195.3 MEDIUMNATS is vulnerable to pre-auth DoS through WebSockets client service
CVE-2026-332224.9 MEDIUMNATS JetStream has an authorization bypass through its Management API
CVE-2026-332494.3 MEDIUMNATS: Message tracing can be redirected to arbitrary subject
CVE-2026-332484.2 MEDIUMNATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching

IV. Related Vulnerabilities

Same product: nats-server
Same vendor: nats-io
Same weakness: CWE-190

V. Comments for CVE-2026-27889

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