Bug 2447144 (CVE-2026-1525)

Summary:	CVE-2026-1525 undici: Undici: HTTP Request Smuggling and Denial of Service due to duplicate Content-Length headers
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aazores, abarbaro, alizardo, anpicker, asoldano, bbaranow, bmaxwell, bparees, brian.stansberry, bstansbe, cmah, darran.lofthouse, dlofthou, 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, thjenkin, tom.jenkinson, vdosoudi, xdharmai, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in undici, a Node.js HTTP/1.1 client. A remote attacker could exploit this vulnerability by sending HTTP/1.1 requests that include duplicate Content-Length headers with different casing (e.g., "Content-Length" and "content-length"). This can lead to HTTP Request Smuggling, a technique where an attacker sends an ambiguous request that is interpreted differently by a proxy and a backend server. Successful exploitation could result in unauthorized access, cache poisoning, or credential hijacking. It may also cause a Denial of Service (DoS) if strict HTTP parsers reject the malformed requests.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2447167, 2447168, 2447170, 2447174
Bug Blocks:

Description OSIDB Bzimport 2026-03-12 21:01:56 UTC

Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire.

Who is impacted:

  *  Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays
  *  Applications that accept user-controlled header names without case-normalization


Potential consequences:

  *  Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request)
  *  HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking

Comment 3 errata-xmlrpc 2026-04-08 13:54:33 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:7080 https://access.redhat.com/errata/RHSA-2026:7080

Comment 4 errata-xmlrpc 2026-04-08 18:04:50 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:7123 https://access.redhat.com/errata/RHSA-2026:7123

Comment 5 errata-xmlrpc 2026-04-09 12:47:14 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:7302 https://access.redhat.com/errata/RHSA-2026:7302

Comment 6 errata-xmlrpc 2026-04-09 13:19:55 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:7310 https://access.redhat.com/errata/RHSA-2026:7310

Comment 7 errata-xmlrpc 2026-04-09 20:20:45 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:7350 https://access.redhat.com/errata/RHSA-2026:7350

Comment 8 errata-xmlrpc 2026-04-13 02:23:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:7675 https://access.redhat.com/errata/RHSA-2026:7675

Comment 9 errata-xmlrpc 2026-04-13 02:47:35 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:7670 https://access.redhat.com/errata/RHSA-2026:7670

Comment 11 errata-xmlrpc 2026-04-14 06:52:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:7983 https://access.redhat.com/errata/RHSA-2026:7983

Comment 12 errata-xmlrpc 2026-05-26 03:53:49 UTC

This issue has been addressed in the following products:

  Cryostat 4 on RHEL 9

Via RHSA-2026:17789 https://access.redhat.com/errata/RHSA-2026:17789