CVE-2024-25622: H2O ignores headers configuration directives

Vulnerability summary

CVE-2024-25622 is a medium (CVSS 4.3) vulnerability in dena h2o. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 40.1% of scored vulnerabilities. 1 public exploit is recorded.

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. The configuration directives provided by the headers handler allows users to modify the response headers being sent by h2o. The configuration file of h2o has scopes, and the inner scopes (e.g., path level) are expected to inherit the configuration defined in outer scopes (e.g., global level). However, if a header directive is used in the inner scope, all the definition in outer scopes are ignored. This can lead to headers not being modified as expected. Depending on the headers being added or removed unexpectedly, this behavior could lead to unexpected client behavior. This vulnerability is fixed in commit 123f5e2b65dcdba8f7ef659a00d24bd1249141be.

• CWE-670Always-Incorrect Control Flow ImplementationThe code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated.