CVE-2026-54340
- Source
- https://cve.org/CVERecord?id=CVE-2026-54340
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54340.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-54340
- Aliases
-
- GHSA-qcrr-wrhc-pgq9
- Downstream
- Published
- 2026-07-16T23:29:50.799Z
- Modified
- 2026-07-19T03:31:10.342590147Z
- Severity
-
- 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- h2o has HTTP/2 state amplification
- Details
-
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.
- Database specific
{ "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54340.json", "cna_assigner": "GitHub_M", "unresolved_ranges": [ { "source": "AFFECTED_FIELD", "extracted_events": [ { "fixed": "9265bdd" } ] } ], "cwe_ids": [ "CWE-400", "CWE-770" ] }- References
Affected packages
Git / github.com/h2o/h2o
Affected versions
v0.*
v0.9.1
v0.9.2
v1.*
v1.0.1
v1.1.0
v1.1.1
v1.2.0
v1.3.0
v1.3.0-beta1
v1.3.1
v1.4.0
v1.4.1
v1.4.2
v1.5.0
v1.5.0-beta1
v1.5.0-beta2
v1.5.0-beta3
v1.5.0-beta4
v1.5.1
v1.5.2
v1.5.3
v1.6.0
v1.6.0-beta1
v1.6.0-beta2
v1.7.0
v1.7.0-beta1
v1.7.0-beta2
v1.7.0-beta3
v1.7.0-beta4
v1.7.0-beta5