{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-54340", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-12T19:23:22.316Z", "datePublished": "2026-07-16T23:29:50.799Z", "dateUpdated": "2026-07-16T23:29:50.799Z"}, "containers": {"cna": {"title": "h2o has HTTP/2 state amplification", "problemTypes": [{"descriptions": [{"cweId": "CWE-400", "lang": "en", "description": "CWE-400: Uncontrolled Resource Consumption", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-770", "lang": "en", "description": "CWE-770: Allocation of Resources Without Limits or Throttling", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/h2o/h2o/security/advisories/GHSA-qcrr-wrhc-pgq9", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/h2o/h2o/security/advisories/GHSA-qcrr-wrhc-pgq9"}, {"name": "https://github.com/h2o/h2o/commit/9265bdd9a996ed992681055e3996baf3e09d2063", "tags": ["x_refsource_MISC"], "url": "https://github.com/h2o/h2o/commit/9265bdd9a996ed992681055e3996baf3e09d2063"}], "affected": [{"vendor": "h2o", "product": "h2o", "versions": [{"version": "< 9265bdd", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-07-16T23:29:50.799Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-qcrr-wrhc-pgq9", "discovery": "UNKNOWN"}}}}

{}

{}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[0,9265bdd)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "h2o", "source": "cna", "vendor": "h2o"}, "product": "h2o", "vendor": "h2o"}], "created": "2026-07-17T01:30:08.117643+00:00", "updated": "2026-07-17T01:30:08.117661+00:00", "vendors": ["h2o", "h2o$PRODUCT$h2o"]}