PT-2026-86519 · Pypi · H3

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CVE-2026-86250

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Published

2026-03-23

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Updated

2026-09-06

CVSS v4.0

8.7

High

VectorAV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Name of the Vulnerable Software and Affected Versions h3 versions prior to 2.0.1-rc.18
Description The software fails to validate the chunk count parsed from user-controlled cookie values within the setChunkedCookie() and deleteChunkedCookie() functions. An attacker can send a crafted cookie header containing an extremely large chunk count to trigger an O(n²) cleanup loop, which results in the server process hanging.
Recommendations Update h3 to version 2.0.1-rc.18 or later.

Exploit

Fix

DoS

Resource Exhaustion

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Weakness Enumeration

Related Identifiers

CVE-2026-86250
GHSA-Q5PR-72PQ-83V3

Affected Products

H3