Bug 2573465 (CVE-2026-128124)

Summary:	CVE-2026-128124 aiohttp: aiohttp: Denial of Service via inefficient domain mask wildcard matching
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	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in aiohttp. A remote attacker can cause a Denial of Service (DoS) by sending HTTP requests with specially crafted, long Host headers to an application configured with multiple wildcards in domain routing masks. Due to inefficient pattern matching, evaluating these headers against multiple wildcards consumes excessive processing time, which stalls the asynchronous event loop and prevents the server from handling legitimate traffic.	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 2026-11-13 20:31:35 UTC

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, Application.add_domain() converts every asterisk wildcard in a domain mask into a greedy regular-expression fragment, so a mask containing two or more wildcards can take polynomial time to reject a long Host header that does not match. A remote attacker can repeatedly send such headers to a server configured with a multi-wildcard domain mask and stall the event loop. This issue is fixed in version 3.14.4.