[USN-7892-1] H2O vulnerability

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Ubuntu Security Notice USN-7892-1
November 26, 2025

h2o vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

H2O could be made to crash if it received specially crafted network traffic.

Software Description:
- h2o: the optimized HTTP/1, HTTP/2 server

Details:

It was discovered that H2O exhibited poor server resource management in its
HTTP/2 protocol. An attacker could possibly use this issue to cause H2O to
crash, resulting in a denial of service.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 22.04 LTS
h2o 2.2.5+dfsg2-6.1ubuntu2+esm1
Available with Ubuntu Pro
libh2o0.13 2.2.5+dfsg2-6.1ubuntu2+esm1
Available with Ubuntu Pro

Ubuntu 20.04 LTS
h2o 2.2.5+dfsg2-3ubuntu0.1~esm1
Available with Ubuntu Pro
libh2o0.13 2.2.5+dfsg2-3ubuntu0.1~esm1
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-7892-1
CVE-2023-44487