Bug 2548339 (CVE-2026-78659)

Summary:	CVE-2026-78659 net/http: golang.org/x/net/http2: golang: net/http: Denial of Service via HTTP/2 trailer header memory exhaustion
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, 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, dhanak, diagrawa, dkeler, dmayorov, dnakabaa, doconnor, dpaolell, drosa, dschmidt, dsimansk, dymurray, eaguilar, ebaron, eborisov, eglynn, ehelms, flucifre, ggainey, gmeno, gparvin, groman, hasun, ibolton, 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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Go net/http package. A remote attacker can trigger a Denial of Service (DoS) by sending HTTP/2 requests that declare an excessive number of trailer header fields. Because the server bypasses configured header limits when allocating memory for these declarations, an attacker can exhaust system memory resources and cause the application to crash.	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:

Description OSIDB Bzimport 2026-10-08 23:01:32 UTC

When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.