What is CVE-2026-44433?

CVE-2026-44433 is a medium-severity vulnerability in H2o Quicly, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-07-16.

How severe is CVE-2026-44433?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Resource exhaustion in H2o Quicly

CVE-2026-44433

Quicly is an IETF QUIC protocol implementation intended primarily for use within the H2O HTTP server. Prior to commit 8b178e6, an adversarial peer could send a STREAM frame carrying just one byte at the largest offset being permitted to ob…

Vulnerability class: DoS (Denial of Service)

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

H2o Quicly — versions < 8b178e6

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption
CWE-770 — Allocation of Resources Without Limits or Throttling

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-44433?: CVE-2026-44433 is a medium-severity vulnerability in H2o Quicly, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-07-16.
How severe is CVE-2026-44433?: Medium severity. CVSS v3 base score is 5.3 out of 10.