CVE-2026-86250

HighCVSS 7.5/10Last modified Sep 18, 2026

Description

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.

Metrics

CVSS 3.1 7.5/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness enumeration

CWE-400

Affected software

Source: the vendor's advisory (CNA). NVD analysis pending.

Vendor	Product	Versions
h3js	h3	>= 2.0.0-beta.4, < 2.0.1-rc.18

References

Timeline

Published: Sep 6, 2026
Last modified: Sep 18, 2026
NVD status: Awaiting Analysis

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