Bug 2543255 (CVE-2026-97687)

Summary: CVE-2026-97687 urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abarbaro, adinn, akhatavk, alinfoot, alizardo, anpicker, anthomas, aos-team-art-private, aprice, asdas, asegurap, bbrownin, blitton, brasmith, cahl, cmyers, cochase, crizzo, dfreiber, dkeler, dnakabaa, doconnor, dpaolell, dranck, drow, dschmidt, dtrifiro, dymurray, eborisov, ebourniv, eglynn, ehelms, fzakkak, galder, gbenhaim, ggainey, gparvin, gtanzill, hasun, hoberger, ibolton, ilpinto, jbalunas, jburrell, jbuscemi, jchui, jdelft, jdobes, jfula, jhe, jholecek, jjoyce, jlanda, jmatthew, jmitchel, jmontleo, jowilson, jpasqual, jpretori, jsamir, jschluet, jupierce, juwatts, jwong, kaycoth, kbempah, kgaikwad, kshier, ktsao, lball, lbrazdil, lcouzens, lgarciaa, lhh, ljawale, lpele, ltomasbo, mbabacek, mbarnett, mbiarnes, mburns, mdellweg, mgarciac, mhayden, mhulan, mminar, mrunge, msilmser, mwoodson, nboldt, ngough, niyer, nmoumoul, nyancey, oaljalju, oezr, olubyans, omaciel, ometelka, orabin, osousa, pakotvan, pcreech, pgaikwad, pjindal, ppalepu, ppostler, prdhamdh, prwatson, psrna, ptisnovs, rbiba, rbobbitt, rchan, rekumar, rhaigner, rhel-process-autobot, rjohnson, sarad, sbiarozk, sbunciak, sdoran, sgehwolf, sghai, sidsharm, simaishi, slucidi, smallamp, solenoci, sprizend, sseago, sskracic, stcannon, sthirugn, suppawar, syedriko, thason, tmalecek, tpfromme, tqvarnst, tsze, twaugh, veshanka, vimartin, vkumar, vlaad, vvoronko, watson-tool-maintainers, weaton, xdharmai, yguenane, ykashtan, zzhou
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in urllib3. This vulnerability allows a remote attacker on the network to intercept and alter data transmitted through an HTTPS proxy. The issue occurs when target-server Transport Layer Security (TLS) settings inadvertently overwrite the proxy's TLS configuration, which can disable certificate verification on reused connection contexts. Consequently, an attacker can impersonate the proxy to monitor or modify forwarded traffic or capture client credentials.
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Last Closed: Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-29 15:54:30 UTC
urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.

Comment 1 Jon Orris 2026-10-19 01:53:26 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:84578 https://access.redhat.com/errata/RHSA-2026:84578

Comment 2 Jon Orris 2026-10-19 01:56:38 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:84577 https://access.redhat.com/errata/RHSA-2026:84577

Comment 3 Jon Orris 2026-10-20 12:26:14 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:85930 https://access.redhat.com/errata/RHSA-2026:85930

Comment 4 Jon Orris 2026-10-20 12:58:36 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:85929 https://access.redhat.com/errata/RHSA-2026:85929

Comment 5 Jon Orris 2026-10-26 21:26:45 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:90494 https://access.redhat.com/errata/RHSA-2026:90494

Comment 7 Jon Orris 2026-10-29 16:24:12 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:92474 https://access.redhat.com/errata/RHSA-2026:92474

Comment 10 Jon Orris 2026-11-05 19:40:23 UTC
This issue has been addressed in the following products:

  Red Hat Satellite 6.17 for RHEL 9

Via RHSA-2026:95656 https://access.redhat.com/errata/RHSA-2026:95656

Comment 11 Jon Orris 2026-11-05 19:44:28 UTC
This issue has been addressed in the following products:

  Red Hat Satellite 6.18 for RHEL 9

Via RHSA-2026:95657 https://access.redhat.com/errata/RHSA-2026:95657

Comment 12 Jon Orris 2026-11-05 19:44:46 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-2026:95655 https://access.redhat.com/errata/RHSA-2026:95655

Comment 13 errata-xmlrpc 2026-11-11 01:15:52 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:98096 https://access.redhat.com/errata/RHSA-2026:98096

Comment 14 errata-xmlrpc 2026-11-11 01:44:53 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:98097 https://access.redhat.com/errata/RHSA-2026:98097

Comment 15 errata-xmlrpc 2026-11-11 01:45:15 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:98098 https://access.redhat.com/errata/RHSA-2026:98098

Comment 16 errata-xmlrpc 2026-11-11 01:51:47 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:98125 https://access.redhat.com/errata/RHSA-2026:98125

Comment 17 errata-xmlrpc 2026-11-11 01:57:39 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:98126 https://access.redhat.com/errata/RHSA-2026:98126

Comment 18 errata-xmlrpc 2026-11-11 01:58:53 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:98122 https://access.redhat.com/errata/RHSA-2026:98122