CVE intelligence and bounded remediation

CVE-2023-41337 — h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. In version 2.3.0-beta2 and prior, when h2o is configured to listen to multiple addresses or ports with each of them using different backend servers managed by multiple entities, a malicious backend entity that also has the opportunity to observe or inject packets exchanged between the client and h2o may misdirect HTTPS requests going to other backends and observe the contents of that HTTPS request being sent. The attack involves a victim client trying to resume a TLS connection and an attacker redirecting the packets to a different address or port than that intended by the client. The attacker must already have been configured by the administrator of h2o to act as a backend to one of the addresses or ports that the h2o instance listens to. Session IDs and tickets generated by h2o are not bound to information specific to the server address, port, or the X.509 certificate, and therefore it is possible for an attacker to force the victim connection to wrongfully resume against a different server address or port on which the same h2o instance is listening. Once a TLS session is misdirected to resume to a server addres…

Severity

Medium

CVSS

6.7 (3.1)

Published

2023-12-12

CISA KEV

Not currently listed

Ecosystem

software/application

Weaknesses

CWE-347