Bug 2506531 (CVE-2026-44909)

Summary: CVE-2026-44909 proxygen: Proxygen: Denial of Service via HTTP/2 flow-control manipulation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Proxygen. A remote, unauthenticated attacker could exploit a missing slow-consumer detection mechanism in the HTTP/2 protocol. By manipulating HTTP/2 flow-control settings, an attacker can force the server to buffer large amounts of data in memory indefinitely. This can lead to unbounded memory growth, causing resource exhaustion, service degradation, or a denial of service (DoS) for affected systems.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2509187    
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Description OSIDB Bzimport 2026-07-23 17:02:12 UTC 
Proxygen lacked a generalized slow-consumer detection mechanism in its core HTTP session layer. A remote, unauthenticated attacker could exploit HTTP/2 flow-control by setting SETTINGS_INITIAL_WINDOW_SIZE to 0 or withholding WINDOW_UPDATE frames, causing the server to buffer complete response bodies in memory indefinitely for stalled streams. By opening many simultaneous streams requesting large resources while preventing the server from transmitting responses, an attacker could induce unbounded memory growth leading to service degradation, resource exhaustion, or denial of service. Versions v2017.01.16.00 through v2026.07.20.00 are affected.