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CVE-2026-6733— undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse

Quick assessment

Affected
undici undici
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
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 6.26.0之前版本、7.28.0之前版本和8.5.0之前版本存在安全漏洞，该漏洞源于HTTP/1.1客户端在重用keep-alive连接时容易受到响应队列投毒攻击，攻击者控制的服务器可以在空闲socket上注入未经请求的HTTP/1.1响应，导致响应被错误分发。

CVSS 3.7 · Low EPSS 0.27% · P18

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-2026-6733

Vulnerability Information
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Vulnerability Title
undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
Source: CVE Program / CVE List V5
Vulnerability Description
Impact: Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests. This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: Disable keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
Node.js undici 竞争条件问题漏洞
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 6.26.0之前版本、7.28.0之前版本和8.5.0之前版本存在安全漏洞，该漏洞源于HTTP/1.1客户端在重用keep-alive连接时容易受到响应队列投毒攻击，攻击者控制的服务器可以在空闲socket上注入未经请求的HTTP/1.1响应，导致响应被错误分发。
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-2026-6733

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III. Intelligence Information for CVE-2026-6733

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Vendor Advisories for CVE-2026-6733 (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-2026-6734 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-2026-11525 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-367

V. Comments for CVE-2026-6733

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