CVE-2026-44453
7.5 · HIGHOverview
CVE-2026-44453 is a high-severity vulnerability affecting h2o h2o. It was published on July 16, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from h2o. Update h2o to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| h2o | h2o | >= 0, < 2026-05-29 | Affected |
Frequently Asked Questions
What is CVE-2026-44453?
CVE-2026-44453 is a high-severity vulnerability affecting h2o h2o. It was published on July 16, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-44453?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-44453?
Check the references section for vendor advisories and patches from h2o. Update h2o to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-44453?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-44453 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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