CVE-2023-30847 H2O vulnerable to read from uninitialized pointer in the reverse proxy handler

High 8.2 Published 27 Apr 2023 Updated 30 Jan 2025

An attacker can cause crashes or leak sensitive information to backend servers by sending invalid HTTP requests to the H2O reverse proxy handler.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2023-30847?

CVE-2023-30847 is a high-severity vulnerability in h2o, published on 27 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the `master` branch in commit f010336. Users should upgrade to commit f010336 or later.

Weakness: CWE-824

Which versions are affected by CVE-2023-30847?

It affects 1 product.

Products include Dena H2o.

How do I fix CVE-2023-30847?

No fix has been published for CVE-2023-30847 yet. Limit exposure of the affected software until one is available.

Is CVE-2023-30847 being exploited?

There is no known exploitation of CVE-2023-30847 in the wild and no public exploit code.

Sources

Also known as GHSA-p5hj-phwj-hrvx, UBUNTU-CVE-2023-30847.