SEPTEMBER 8, 2026
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Case File

CVE-2026-44453

HIGH · CVSS 7.5 EPSS 0.28% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-16 · Last synced 2026-08-15

CyberRota Analysis

AI-Generated

The h2o HTTP server is vulnerable to a Denial of Service attack due to improper handling of stack memory allocation when serving static files, which can lead to a segmentation fault and server crash. This issue arises when the memory allocated exceeds the default pthread stack size, potentially causing service interruptions. Organizations using h2o should prioritize this vulnerability to ensure server stability and prevent potential downtime.

Public Exploit Signal

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

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

CVE
CVE-2026-44453
Severity
HIGH
CVSS
7.5
EPSS
0.28%

Original NVD Description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 6b5370d, h2o is vulnerable to a Denial of Service attack when calling alloca under certain conditions. When serving static files, h2o builds the file path on stack, by calling alloca. The maximum size of the memory allocated using alloca can be as huge as ~600KB, which exceeds the default pthread stack size used by musl libc (128KB). If the amount of memory allocated by alloca exceeds the stack size, the h2o server crashes with a segmentation fault, while it tries to touch the guard page. This issue has been fixed by commit 6b5370d.

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