Bug 2447141 (CVE-2026-1527)

Summary: CVE-2026-1527 undici: Undici: HTTP header injection and request smuggling vulnerability
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: aazores, abarbaro, alizardo, anpicker, asoldano, bbaranow, bmaxwell, bparees, brian.stansberry, cmah, darran.lofthouse, dosoudil, dschmidt, eaguilar, ebaron, erezende, fjuma, hasun, istudens, ivassile, iweiss, jchui, jfula, jhe, jkoehler, jlanda, jolong, jowilson, kshier, ktsao, lphiri, mosmerov, msvehla, nboldt, nwallace, nyancey, ometelka, pberan, pesilva, pjindal, pmackay, psrna, ptisnovs, rstancel, sdawley, simaishi, smaestri, smcdonal, stcannon, syedriko, teagle, tom.jenkinson, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in undici, a Node.js HTTP/1.1 client. This vulnerability allows a remote attacker to inject malicious data into HTTP headers or prematurely end HTTP requests by sending specially crafted input to the `upgrade` option of `client.request()`. This is possible because undici does not properly validate input for invalid header characters, which could lead to unauthorized information disclosure or bypassing of security controls.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2447172, 2447175, 2447169, 2447178    
Bug Blocks:    

Description OSIDB Bzimport 2026-03-12 21:01:44 UTC
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`
}