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CVE-2026-55213

Is CVE-2026-55213 real, exploitable, or a false positive? Here's the community verdict.

signals

public sources

Exploited in wild
Not listed
CISA KEV
Public exploit
None known
Metasploit/EDB/PoC
Base severity
7.5 High
CVSS
Exploitation prob.
n/a
FIRST EPSS
Weakness
CWE-789
CWE

Moderate signals. Triage by your actual exposure and reachability.

baseline read

auto · not a community verdict

Low signal — verdict needed

Few public signals point to active risk. Whether a scanner hit here is a true or false positive depends on your version and config — community verdicts decide.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.

Published

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In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

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    Same weakness: CWE-789.