CVE-2024-45397: H2O alllows bypassing address-based access control with 0-RTT

Vulnerability summary

CVE-2024-45397 is a high (CVSS 7.5) Improper Access Control vulnerability in dena h2o. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 38.3% of scored vulnerabilities.

Timeline

1. 11-10-2024
   PublishedVulnerability first disclosed.
2. 11-10-2024
   Last modifiedVulnerability information updated.

Description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. When an HTTP request using TLS/1.3 early data on top of TCP Fast Open or QUIC 0-RTT packets is received and the IP-address-based access control is used, the access control does not detect and prohibit HTTP requests conveyed by packets with a spoofed source address. This behavior allows attackers on the network to execute HTTP requests from addresses that are otherwise rejected by the address-based access control. The vulnerability has been addressed in commit 15ed15a. Users may disable the use of TCP FastOpen and QUIC to mitigate the issue.

• CWE-284Improper Access ControlThe product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
• CWE-290Authentication Bypass by SpoofingThis attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.