What is CVE-2026-86250?

CVE-2026-86250 is a high-severity vulnerability in H3js H3, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-09-06.

How severe is CVE-2026-86250?

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

Resource exhaustion in H3js H3

CVE-2026-86250

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie() and deleteChunkedCookie() functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an O(n²) cleanup loop that hangs the server process.

Vulnerability class: DoS (Denial of Service)

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

H3js H3

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-86250?: CVE-2026-86250 is a high-severity vulnerability in H3js H3, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-09-06.
How severe is CVE-2026-86250?: High severity. CVSS v3 base score is 7.5 out of 10.