What is CVE-2026-44453?

CVE-2026-44453 is a high-severity vulnerability in H2o, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-07-16.

How severe is CVE-2026-44453?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in H2o

CVE-2026-44453

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 6b5370d, h2o is vulnerable to a Denial of Service attack when calling alloca under certain conditions. When serving static files, h2o builds the file path…

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

H2o — versions < 6b5370d

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling
CWE-789

References

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

Frequently asked questions

What is CVE-2026-44453?: CVE-2026-44453 is a high-severity vulnerability in H2o, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-07-16.
How severe is CVE-2026-44453?: High severity. CVSS v3 base score is 7.5 out of 10.