Service interruption via stalled HTTP/2 response flow
Published Jul 23, 2026 · Updated Jul 23, 2026
Resource exhaustion in Meta Platforms Proxygen before 2026.07.20.00 allows remote attackers to interrupt service through stalled HTTP/2 streams. The core HTTPSession layer retains complete response bodies in pending write buffers without a slow-consumer limit when peers set SETTINGS_INITIAL_WINDOW_SIZE to zero or withhold WINDOW_UPDATE frames. No authentication or user interaction is required; many concurrent streams requesting large resources cause unbounded memory growth and service exhaustion.
Summary
What happened
Resource exhaustion in Meta Platforms Proxygen before 2026.07.20.00 allows remote attackers to interrupt service through stalled HTTP/2 streams. The core HTTPSession layer retains complete response bodies in pending write buffers without a slow-consumer limit when peers set SETTINGS_INITIAL_WINDOW_SIZE to zero or withhold WINDOW_UPDATE frames. No authentication or user interaction is required; many concurrent streams requesting large resources cause unbounded memory growth and service exhaustion.
The record
- CVE
- CVE-2026-44909
- Published
- Jul 23, 2026
- Updated
- Jul 23, 2026
- Vendor
- Meta Platforms, Inc.
- Product
- Proxygen
- Classifications
- CWE-770, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 23, 2026CVE publishedPublication date reported by the CVE source.
- Jul 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=v2017.01.16.00 <v2026.07.20.00
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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