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CVE-2026-1527— undici is vulnerable to CRLF Injection via upgrade option

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.

undici是Node.js开源的一个HTTP/1.1客户端。 undici存在安全漏洞，该漏洞源于未验证upgrade选项中的用户输入，可能导致攻击者注入CRLF序列以注入任意HTTP标头或提前终止HTTP请求并向非HTTP服务夹带原始数据。

CVSS 4.6 · Medium EPSS 0.28% · P18
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I. Basic Information for CVE-2026-1527

Vulnerability Information
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Vulnerability Title
undici is vulnerable to CRLF Injection via upgrade option
Source: CVE Program / CVE List V5
Vulnerability Description
ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to: * Inject arbitrary HTTP headers * Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch) The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters: // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` }
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对CRLF序列的转义处理不恰当(CRLF注入)
Source: CVE Program / CVE List V5
Vulnerability Title
undici 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
undici是Node.js开源的一个HTTP/1.1客户端。 undici存在安全漏洞，该漏洞源于未验证upgrade选项中的用户输入，可能导致攻击者注入CRLF序列以注入任意HTTP标头或提前终止HTTP请求并向非HTTP服务夹带原始数据。
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 < 6.24.0; 7.0.0 < 7.24.0 -

II. Public POCs for CVE-2026-1527

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III. Intelligence Information for CVE-2026-1527

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Vendor Advisories for CVE-2026-1527 (1)

Same Patch Batch · undici · 2026-03-12 · 6 CVEs total

CVE-2026-1526 7.5 HIGH undici is vulnerable to Unbounded Memory Consumption in undici WebSocket permessage-deflat
CVE-2026-1528 7.5 HIGH undici is vulnerable to Malicious WebSocket 64-bit length overflows undici parser and cras
CVE-2026-2229 7.5 HIGH undici is vulnerable to Unhandled Exception in undici WebSocket Client Due to Invalid serv
CVE-2026-1525 6.5 MEDIUM undici is vulnerable to Inconsistent Interpretation of HTTP Requests ('HTTP Request/Respon
CVE-2026-2581 5.9 MEDIUM undici is vulnerable to Unbounded Memory Consumption in in Undici's DeduplicationHandler v

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-93

V. Comments for CVE-2026-1527

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