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CVE-2026-12151— undici WebSocket client vulnerable to denial of service via fragment count bypass

Quick assessment

Affected
undici undici
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.

Node.js undici是Node.js基金会开源的一个HTTP/1.1客户端。 Node.js undici 6.17.0版本及以上版本存在资源管理错误漏洞，该漏洞源于对WebSocket分片数量未限制，可能导致恶意WebSocket服务器连续发送小或空的延续帧，造成客户端内存耗尽，导致拒绝服务。以下版本受到影响：6.17.0版本及以上版本。

CVSS 7.5 · High EPSS 0.79% · P55

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici < 6.26.0 affected
6.26.0 unaffected
7.0.0< 7.28.0 affected
7.28.0 unaffected
8.0.0< 8.5.0 affected
8.5.0 unaffected
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I. Basic Information for CVE-2026-12151

Vulnerability Information
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Vulnerability Title
undici WebSocket client vulnerable to denial of service via fragment count bypass
Source: CVE Program / CVE List V5
Vulnerability Description
Impact: The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. All releases starting at undici 6.17.0 are affected. Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Node.js undici 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Node.js undici是Node.js基金会开源的一个HTTP/1.1客户端。 Node.js undici 6.17.0版本及以上版本存在资源管理错误漏洞，该漏洞源于对WebSocket分片数量未限制，可能导致恶意WebSocket服务器连续发送小或空的延续帧，造成客户端内存耗尽，导致拒绝服务。以下版本受到影响：6.17.0版本及以上版本。
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
undici undici 0 ~ 6.26.0 -

II. Public POCs for CVE-2026-12151

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 9055 chars
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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
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III. Intelligence Information for CVE-2026-12151

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Vendor Advisories for CVE-2026-12151 (1)

Same Patch Batch · undici · 2026-06-17 · 8 CVEs total

CVE-2026-9675 7.5 HIGH undici WebSocket client vulnerable to denial of service via cumulative fragment bypass
CVE-2026-6734 7.5 HIGH undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse
CVE-2026-9697 7.4 HIGH undici vulnerable to TLS certificate validation bypass via dropped requestTls in SOCKS5 Pr
CVE-2026-9679 5.9 MEDIUM undici vulnerable to HTTP header injection via Set-Cookie percent-decoding
CVE-2026-9678 5.9 MEDIUM undici vulnerable to cross-user information disclosure via shared cache whitespace bypass
CVE-2026-6733 3.7 LOW undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
CVE-2026-11525 3.7 LOW undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matc

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-400

V. Comments for CVE-2026-12151

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