CVE-2026-86250
h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-400 |
| Vendor | h3js |
| Product | h3 |
| Published | Sep 6, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
h3js / h3
2.0.0-beta.4 < 2.0.1-rc.18
References
Credits
🔍 offset