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CVE-2026-6734— undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse

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存在输入验证错误漏洞，该漏洞源于使用Socks5ProxyAgent时，未验证连接池的来源是否与请求的来源匹配，导致跨源请求路由，凭证和请求数据被发送到错误来源，响应被错误信任，且HTTPS请求可能被静默降级为HTTP。以下版本受到影响：7.23.0版本至8.1.0及之前版本。

CVSS 7.5 · High EPSS 0.39% · P31

Affected Version Matrix 4

VendorProduct Version RangeStatus
undici undici 7.23.0< 7.26.0 affected
7.26.0 unaffected
8.0.0< 8.2.0 affected
8.2.0 unaffected
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I. Basic Information for CVE-2026-6734

Vulnerability Information
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Vulnerability Title
undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse
Source: CVE Program / CVE List V5
Vulnerability Description
Impact: When using Socks5ProxyAgent, undici reuses a single connection pool across different origins without verifying that the pool's origin matches the requested origin. All requests are dispatched through the pool connected to the first origin, regardless of the intended destination. This causes cross-origin request routing: credentials and request data intended for origin B are sent to origin A, responses from the wrong origin are trusted, and HTTPS requests may be silently downgraded to HTTP. Impacted users are applications that use Socks5ProxyAgent (directly or via setGlobalDispatcher) and make requests to more than one origin. This was introduced in undici 7.23.0 via PR #4385 and affects all versions through 8.1.0. Patches: Upgrade to undici v7.26.0 or v8.2.0. Workarounds: Use a separate Socks5ProxyAgent instance per origin, or avoid using Socks5ProxyAgent with multiple origins.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5
Vulnerability Title
Node.js undici 输入验证错误漏洞
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存在输入验证错误漏洞，该漏洞源于使用Socks5ProxyAgent时，未验证连接池的来源是否与请求的来源匹配，导致跨源请求路由，凭证和请求数据被发送到错误来源，响应被错误信任，且HTTPS请求可能被静默降级为HTTP。以下版本受到影响：7.23.0版本至8.1.0及之前版本。
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
undici undici 7.23.0 ~ 7.26.0 -

II. Public POCs for CVE-2026-6734

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 10082 chars
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III. Intelligence Information for CVE-2026-6734

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Vendor Advisories for CVE-2026-6734 (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-2026-12151 7.5 HIGH undici WebSocket client vulnerable to denial of service via fragment count bypass
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-346

V. Comments for CVE-2026-6734

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