CVE-2026-54340 - h2o has HTTP/2 state amplification
CVE ID :CVE-2026-54340
Published : July 17, 2026, 12:16 a.m. | 32 minutes ago
Description :h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 9265bdd, there is an HTTP/2 state amplification issue that combines HPACK decompression amplification with Slowloris-style stream stalling. Amplified decoded header state can be retained by stalled HTTP/2 streams, and depending on the configuration, additional limits are needed to bound decoded header state and prevent attack. This issue has been fixed by commit 9265bdd.
Severity: 7.5 | HIGH
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Published : July 17, 2026, 12:16 a.m. | 32 minutes ago
Description :h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 9265bdd, there is an HTTP/2 state amplification issue that combines HPACK decompression amplification with Slowloris-style stream stalling. Amplified decoded header state can be retained by stalled HTTP/2 streams, and depending on the configuration, additional limits are needed to bound decoded header state and prevent attack. This issue has been fixed by commit 9265bdd.
Severity: 7.5 | HIGH
Visit the link for more details, such as CVSS details, affected products, timeline, and more...