CVE-2026-54340
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| h2o | h2o | < 9265bdd | affected |
Weaknesses
- CWE-400: CWE-400: Uncontrolled Resource Consumption
- CWE-770: CWE-770: Allocation of Resources Without Limits or Throttling
References
- https://github.com/h2o/h2o/security/advisories/GHSA-qcrr-wrhc-pgq9
- https://github.com/h2o/h2o/commit/9265bdd9a996ed992681055e3996baf3e09d2063
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