Bug 2539827 (CVE-2026-59980)

Summary:	CVE-2026-59980 hpack: golang.org/x/net/http2/hpack: hpack: Denial of Service via malformed HTTP/2 header encoding
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dschmidt, dymurray, eglynn, ibolton, jjoyce, jlanda, jmatthew, jmontleo, jpretori, jschluet, kaycoth, kshier, lhh, mburns, mgarciac, pgaikwad, rjohnson, simaishi, slucidi, sseago, stcannon, yguenane
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in hpack, an HTTP/2 Header Encoding for Python. Unbounded variable integer decoding can lead to excessive computation when processing specially crafted, malformed input. A remote attacker could exploit this vulnerability to cause a denial of service by effectively blocking further processing within the affected component.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-09-23 22:22:31 UTC

hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.