Bug 2548340 (CVE-2026-78660)

Summary: CVE-2026-78660 net/http: golang: golang.org/x/net/http2: net/http: HTTP response smuggling via malformed HTTP/2 framing headers
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, akhatavk, akostadi, akoudelk, alebedev, alizardo, amasferr, amctagga, anjoseph, anpicker, ansmith, anthomas, aoconnor, aos-team-art-private, asatyam, asdas, bbrownin, blitton, bmuthuka, bniver, chfoley, ckandaga, cmah, cmyers, crizzo, dakwon, dbenoit, dhanak, diagrawa, dkeler, dmayorov, dnakabaa, doconnor, dpaolell, drosa, dschmidt, dsimansk, dymurray, eaguilar, ebaron, eborisov, eglynn, ehelms, flucifre, ggainey, gmeno, gparvin, groman, hasun, ibolton, ikhan, jbalunas, jbritton, jburrell, jcantril, jchui, jdelft, jeder, jfula, jhe, jjoyce, jlanda, jlledo, jmatsuok, jmatthew, jmontleo, jowilson, jpasqual, jprabhak, jpretori, jschluet, jtolenti, jturenov, jupierce, juwatts, kaycoth, kingland, kshier, ktsao, lball, lbragsta, lchilton, lcouzens, lgamliel, lgarciaa, lhh, mbarnett, mbenjamin, mbiarnes, mburns, mdellweg, mgarciac, mhackett, mhulan, mnovotny, mrunge, mszuc, mwringe, nboldt, ngough, nmoumoul, nyancey, oaljalju, ometelka, osousa, pantinor, pcreech, pgaikwad, pjindal, ppalepu, ppostler, prdhamdh, psrna, ptisnovs, pvasanth, pwambui, rbobbitt, rchan, rekumar, rhaigner, rhel-process-autobot, rjohnson, rojacob, sabiswas, sakbas, sausingh, sbratsla, sdawley, sfeifer, sghai, sidsharm, simaishi, slakshmi, slucidi, smallamp, sostapov, sseago, stcannon, suppawar, swoodman, syedriko, thason, tmalecek, tsedmik, tsze, tzivkovi, vereddy, veshanka, vimartin, vkarehfa, vlaad, vvoronko, watson-tool-maintainers, wenshen, whayutin, wscales, wtam, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in Go's net/http package. When operating as a reverse proxy, the HTTP/2 implementation does not properly validate framing-related headers in responses received from upstream servers before forwarding them to downstream HTTP/1 clients. A malicious upstream server can exploit this flaw by sending malformed response headers, resulting in HTTP response smuggling, where message boundaries between the proxy and client become desynchronized. This issue may allow attackers to bypass security controls, poison web caches, or intercept sensitive data from other user sessions.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-08 23:01:37 UTC 
Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.