Bug 2427726 (CVE-2026-21441)

Summary:	CVE-2026-21441 urllib3: urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	abarbaro, adinn, adistefa, alcohan, alinfoot, alizardo, amctagga, anjoseph, anpicker, anthomas, aoconnor, aprice, bbrownin, bdettelb, bniver, bparees, brasmith, cahl, carogers, caswilli, cmyers, cochase, crizzo, dfreiber, dhanak, dnakabaa, doconnor, dranck, drosa, drow, dschmidt, dsimansk, dtrifiro, dymurray, eborisov, eglynn, ehelms, erezende, flucifre, fzakkak, galder, galder.zamarreno, ggainey, gmeno, gparvin, groman, gtanzill, haoli, hasun, hkataria, ibolton, jajackso, jbalunas, jburrell, jbuscemi, jcammara, jcantril, jchui, jdobes, jfula, jhe, jjoyce, jkoehler, jlanda, jmatthew, jmitchel, jmontleo, jneedle, joehler, jowilson, jpasqual, jprabhak, jpretori, jsamir, jschluet, juwatts, jwong, kaycoth, kbempah, kegrant, kgaikwad, kingland, koliveir, kshier, ktsao, kverlaen, lball, lbrazdil, lchilton, lcouzens, lgamliel, lhh, ljawale, lphiri, luizcosta, mabashia, manissin, mattdavi, matzew, mbabacek, mbenjamin, mburns, mgarciac, mhackett, mhayden, mhess, mhulan, mminar, mnovotny, mrunge, msilmser, mskarbek, nboldt, ngough, nmoumoul, nweather, nyancey, oaljalju, oezr, olubyans, omaciel, ometelka, orabin, osousa, owatkins, pahickey, pakotvan, pbraun, pcreech, pgaikwad, pjindal, prwatson, psrna, ptisnovs, rbiba, rbobbitt, rbryant, rchan, rekumar, rfreiman, rhaigner, rhel-process-autobot, rjohnson, rojacob, sausingh, sbiarozk, sbratsla, sdawley, sdoran, sfeifer, sgehwolf, shvarugh, simaishi, slucidi, smallamp, smcdonal, solenoci, sostapov, sseago, sskracic, stcannon, sthirugn, syedriko, teagle, tfister, thavo, tmalecek, tpfromme, tqvarnst, ttakamiy, tzivkovi, vereddy, veshanka, vimartin, vkumar, vle, vvoronko, vwilson, watson-tool-maintainers, weaton, whayutin, wtam, xdharmai, yguenane, zdohnal, zzhou
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:		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:	2428642, 2428643, 2428644, 2428645, 2428646, 2428647, 2428648, 2428649, 2428650, 2428651, 2428730, 2428731, 2431305, 2431306, 2431307, 2431309, 2431310
Bug Blocks:

Description OSIDB Bzimport 2026-01-07 23:02:25 UTC

urllib3 is an HTTP client library for Python. urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. urllib3 can perform decoding or decompression based on the HTTP `Content-Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API, the library decompresses only the necessary bytes, enabling partial content consumption. Starting in version 1.22 and prior to version 2.6.3, for HTTP redirect responses, the library would read the entire response body to drain the connection and decompress the content unnecessarily. This decompression occurred even before any read methods were called, and configured read limits did not restrict the amount of decompressed data. As a result, there was no safeguard against decompression bombs. A malicious server could exploit this to trigger excessive resource consumption on the client. Applications and libraries are affected when they stream content from untrusted sources by setting `preload_content=False` when they do not disable redirects. Users should upgrade to at least urllib3 v2.6.3, in which the library does not decode content of redirect responses when `preload_content=False`. If upgrading is not immediately possible, disable redirects by setting `redirect=False` for requests to untrusted source.

Comment 1 errata-xmlrpc 2026-01-26 12:38:23 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:1086 https://access.redhat.com/errata/RHSA-2026:1086

Comment 2 errata-xmlrpc 2026-01-26 12:59:37 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:1087 https://access.redhat.com/errata/RHSA-2026:1087

Comment 3 errata-xmlrpc 2026-01-26 14:06:26 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:1089 https://access.redhat.com/errata/RHSA-2026:1089

Comment 4 errata-xmlrpc 2026-01-26 14:14:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:1088 https://access.redhat.com/errata/RHSA-2026:1088

Comment 5 errata-xmlrpc 2026-01-26 14:58:02 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1224 https://access.redhat.com/errata/RHSA-2026:1224

Comment 6 errata-xmlrpc 2026-01-26 15:29:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1226 https://access.redhat.com/errata/RHSA-2026:1226

Comment 7 errata-xmlrpc 2026-01-26 17:54:57 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1241 https://access.redhat.com/errata/RHSA-2026:1241

Comment 8 errata-xmlrpc 2026-01-26 17:59:20 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:1239 https://access.redhat.com/errata/RHSA-2026:1239

Comment 9 errata-xmlrpc 2026-01-26 18:13:58 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1240 https://access.redhat.com/errata/RHSA-2026:1240

Comment 10 errata-xmlrpc 2026-01-26 20:44:19 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:1254 https://access.redhat.com/errata/RHSA-2026:1254

Comment 11 errata-xmlrpc 2026-01-28 11:21:51 UTC

This issue has been addressed in the following products:

  RHUI 4 for RHEL 8

Via RHSA-2026:1485 https://access.redhat.com/errata/RHSA-2026:1485

Comment 12 errata-xmlrpc 2026-01-29 09:08:38 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:1546 https://access.redhat.com/errata/RHSA-2026:1546

Comment 13 errata-xmlrpc 2026-02-02 01:12:42 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

Via RHSA-2026:1618 https://access.redhat.com/errata/RHSA-2026:1618

Comment 14 errata-xmlrpc 2026-02-02 01:53:12 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:1619 https://access.redhat.com/errata/RHSA-2026:1619

Comment 15 errata-xmlrpc 2026-02-02 06:38:12 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:1674 https://access.redhat.com/errata/RHSA-2026:1674

Comment 16 errata-xmlrpc 2026-02-02 06:49:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:1676 https://access.redhat.com/errata/RHSA-2026:1676

Comment 17 errata-xmlrpc 2026-02-02 09:57:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:1693 https://access.redhat.com/errata/RHSA-2026:1693

Comment 18 errata-xmlrpc 2026-02-02 11:45:17 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:1704 https://access.redhat.com/errata/RHSA-2026:1704

Comment 19 errata-xmlrpc 2026-02-02 12:28:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:1706 https://access.redhat.com/errata/RHSA-2026:1706

Comment 20 errata-xmlrpc 2026-02-02 13:05:51 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:1712 https://access.redhat.com/errata/RHSA-2026:1712

Comment 21 errata-xmlrpc 2026-02-02 14:01:59 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:1717 https://access.redhat.com/errata/RHSA-2026:1717

Comment 22 errata-xmlrpc 2026-02-02 15:18:51 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:1726 https://access.redhat.com/errata/RHSA-2026:1726

Comment 23 errata-xmlrpc 2026-02-02 15:38:29 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:1729 https://access.redhat.com/errata/RHSA-2026:1729

Comment 24 errata-xmlrpc 2026-02-02 17:37:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

Via RHSA-2026:1734 https://access.redhat.com/errata/RHSA-2026:1734

Comment 25 errata-xmlrpc 2026-02-02 17:41:41 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:1735 https://access.redhat.com/errata/RHSA-2026:1735

Comment 26 errata-xmlrpc 2026-02-03 07:14:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.6 Telecommunications Update Service

Via RHSA-2026:1793 https://access.redhat.com/errata/RHSA-2026:1793

Comment 27 errata-xmlrpc 2026-02-03 07:14:43 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:1791 https://access.redhat.com/errata/RHSA-2026:1791

Comment 28 errata-xmlrpc 2026-02-03 07:15:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:1794 https://access.redhat.com/errata/RHSA-2026:1794

Comment 29 errata-xmlrpc 2026-02-03 07:16:49 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.6 Telecommunications Update Service

Via RHSA-2026:1792 https://access.redhat.com/errata/RHSA-2026:1792

Comment 30 errata-xmlrpc 2026-02-03 09:40:51 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:1803 https://access.redhat.com/errata/RHSA-2026:1803

Comment 31 errata-xmlrpc 2026-02-03 10:15:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:1805 https://access.redhat.com/errata/RHSA-2026:1805

Comment 32 errata-xmlrpc 2026-02-04 19:11:24 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:1957 https://access.redhat.com/errata/RHSA-2026:1957

Comment 34 errata-xmlrpc 2026-02-16 11:23:42 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:2723 https://access.redhat.com/errata/RHSA-2026:2723

Comment 35 errata-xmlrpc 2026-02-16 11:26:59 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.6 Telecommunications Update Service

Via RHSA-2026:2717 https://access.redhat.com/errata/RHSA-2026:2717

Comment 36 errata-xmlrpc 2026-02-16 11:36:01 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:2718 https://access.redhat.com/errata/RHSA-2026:2718

Comment 37 errata-xmlrpc 2026-02-16 11:53:54 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.2 Advanced Update Support

Via RHSA-2026:2728 https://access.redhat.com/errata/RHSA-2026:2728

Comment 38 errata-xmlrpc 2026-02-16 16:48:16 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.18 for RHEL 9

Via RHSA-2026:2760 https://access.redhat.com/errata/RHSA-2026:2760

Comment 39 errata-xmlrpc 2026-02-16 19:02:48 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.17 for RHEL 9

Via RHSA-2026:2764 https://access.redhat.com/errata/RHSA-2026:2764

Comment 40 errata-xmlrpc 2026-02-16 21:29:48 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.16 for RHEL 8
  Red Hat Satellite 6.16 for RHEL 9

Via RHSA-2026:2765 https://access.redhat.com/errata/RHSA-2026:2765

Comment 41 errata-xmlrpc 2026-02-18 09:52:37 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7 Extended Lifecycle Support

Via RHSA-2026:2911 https://access.redhat.com/errata/RHSA-2026:2911

Comment 47 errata-xmlrpc 2026-06-22 20:54:48 UTC

This issue has been addressed in the following products:

  Red Hat OpenStack Platform 17.1 for RHEL 8

Via RHSA-2026:28043 https://access.redhat.com/errata/RHSA-2026:28043