SEPTEMBER 17, 2026
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Case File

CVE-2026-86250

HIGH · CVSS 7.5 EPSS 0.28% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-06 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

Versions of h3 prior to 2.0.1-rc.18 are vulnerable due to inadequate validation of chunk counts in user-controlled cookie values, specifically in the setChunkedCookie() and deleteChunkedCookie() functions. This flaw allows attackers to exploit the server by sending a malicious cookie header, resulting in an O(n²) cleanup loop that can hang the server process, potentially leading to denial of service. Organizations using affected versions should prioritize patching to mitigate this high-severity vulnerability.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-86250
Severity
HIGH
CVSS
7.5
EPSS
0.28%

Original NVD 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.