CVE-2025-57804 – h2

Package

Manager: pip
Name: h2
Vulnerable Version: >=0 <4.3.0

Severity

Level: Medium

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

EPSS: 0.00062 pctl0.19559

Details

h2 allows HTTP Request Smuggling due to illegal characters in headers ### Summary HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls.

Metadata

Created: 2025-08-25T20:44:43Z
Modified: 2025-08-26T17:11:23Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/08/GHSA-847f-9342-265h/GHSA-847f-9342-265h.json
CWE IDs: ["CWE-93"]
Alternative ID: GHSA-847f-9342-265h
Finding: F184
Auto approve: 1