HIGHCVSS v3.1 7.5Vulnerability
CVE-2026-55367
h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 4212ce114506a073505fd389db16ad2ba4e582a0, a client could send an incomplete CONNECT-UDP Capsule with an excessively large declared length, causing H2O to keep buffering received bytes without a per-Capsule limit while waiting for the remainder. Deployments that enabled proxy.connect-udp and accepted CONNECT-UDP requests could exhaust server memory and lose availability. This vulnerability is fixed with commit 4212ce114506a073505fd389db16ad2ba4e582a0.
Properties
- Severity
- HIGH
- Nvd fetched at
- 2026-11-05T01:47:04.832199+00:00
- Cvss severity
- HIGH
- Cvss score
- 7.5
- Retrieved at
- 2026-11-05T01:47:49+00:00
- Score
- 7.5
- Cvss version
- 3.1
- Last source
- NVD
- Cve id
- CVE-2026-55367
- Cvss vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- First seen by Signal
- 2026-11-05T01:42:37+00:00
- Name
- CVE-2026-55367
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published at
- 2026-11-04T22:18:06.167
- Last modified
- 2026-11-04T22:18:06.167
Related Entities (1)
HAS_WEAKNESS (1)
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