{"id":"UBUNTU-CVE-2026-59980","details":"hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.","modified":"2026-09-25T06:36:30.372568117Z","published":"2026-09-24T00:00:00Z","upstream":["CVE-2026-59980"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-59980"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-59980"},{"type":"REPORT","url":"https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"},{"type":"REPORT","url":"https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"},{"type":"REPORT","url":"https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"},{"type":"REPORT","url":"https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"},{"type":"REPORT","url":"https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"}],"affected":[{"package":{"name":"python-hpack","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-1","2.0.1-1","2.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python-hpack","binary_version":"2.1.0-1"},{"binary_name":"python3-hpack","binary_version":"2.1.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}},{"package":{"name":"python-hpack","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.0-1","3.0.0-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python-hpack","binary_version":"3.0.0-2"},{"binary_name":"python3-hpack","binary_version":"3.0.0-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}},{"package":{"name":"python-hpack","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.0-3","3.0.0-4"],"ecosystem_specific":{"binaries":[{"binary_version":"3.0.0-4","binary_name":"python3-hpack"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}},{"package":{"name":"python-hpack","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.0-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-hpack","binary_version":"4.0.0-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}},{"package":{"name":"python-hpack","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.0-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-hpack","binary_version":"4.0.0-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}},{"package":{"name":"python-hpack","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/python-hpack?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.0-3"],"ecosystem_specific":{"binaries":[{"binary_version":"4.0.0-3","binary_name":"python3-hpack"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-59980.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}