{"id":"UBUNTU-CVE-2025-57804","details":"h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an 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. This issue has been patched in version 4.3.0.","modified":"2026-05-20T16:11:25.675504587Z","published":"2025-08-25T21:15:00Z","upstream":["CVE-2025-57804"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2025-57804"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2025-57804"},{"type":"REPORT","url":"https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h"}],"affected":[{"package":{"name":"python-h2","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.1-1","3.0.1-2","3.0.1-3"],"ecosystem_specific":{"binaries":[{"binary_name":"python-h2","binary_version":"3.0.1-3"},{"binary_name":"python3-h2","binary_version":"3.0.1-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}},{"package":{"name":"python-h2","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.1-4","3.0.1-4.1ubuntu1","3.0.1-5","3.1.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-h2","binary_version":"3.1.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}},{"package":{"name":"python-h2","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.0-3","4.1.0-3ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-h2","binary_version":"4.1.0-3ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}},{"package":{"name":"python-h2","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0-4"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-h2","binary_version":"4.1.0-4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}},{"package":{"name":"python-h2","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0-4","4.2.0-1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.2.0-1","binary_name":"python3-h2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}},{"package":{"name":"python-h2","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/python-h2?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.2.0-1","4.3.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-h2","binary_version":"4.3.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-57804.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}