{"schema":"threatline.record/2","record":{"id":"CVE-2026-59980","aliases":["GHSA-8v8h-hg4w-mvq2","PYSEC-2026-4053"],"summary":"hpack: Unbounded variable integer decoding can cause run-away computation on malformed input","details":"### Impact\n\nUsers of the python-hyper/hpack library, most commonly used as downstream dependency of the python-hyper/h2 library (an HTTP/2 client and server implementation). 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.\n\n### Patches\nA fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation.\n\n### Workarounds\nSanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.","categories":["Runtimes & languages"],"product":"hpack","vendor":"python-hyper","ecosystem":"pip","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-8v8h-hg4w-mvq2","source_modified_at":"2026-09-24T19:43:27Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"hpack"},"range":"<= 4.1.0"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-59980","source_modified_at":"2026-09-24T13:25:08.900Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"hpack","vendor":"python-hyper","versions":[{"version":"< 4.2.0","status":"affected"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-8v8h-hg4w-mvq2","source_modified_at":"2026-10-01T17:55:38.238084125Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"hpack","ecosystem":"PyPI","purl":"pkg:pypi/hpack"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.2.0"}]}],"versions":["1.0.0","1.0.1","1.1.0","2.0.0","2.0.1","2.1.0","2.1.1","2.2.0","2.3.0","3.0.0","4.0.0","4.1.0"]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-8v8h-hg4w-mvq2","source_modified_at":"2026-09-24T19:43:27Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"hpack"},"version":"4.2.0"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-8v8h-hg4w-mvq2","source_modified_at":"2026-10-01T17:55:38.238084125Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"hpack","ecosystem":"PyPI","purl":"pkg:pypi/hpack"},"version":"4.2.0"}],"cvss":6.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00301,"percentile":0.21706,"score_date":"2026-10-23"},"published_at":"2026-09-23T22:07:35.095Z","modified_at":"2026-10-01T17:55:38.238084125Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-8v8h-hg4w-mvq2","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-09-24T19:43:27Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-59980","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-09-24T13:25:08.900Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-8v8h-hg4w-mvq2","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-01T17:55:38.238084125Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-59980","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2","tags":["x_refsource_CONFIRM"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59980","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403","tags":["x_refsource_MISC"]},{"url":"https://github.com/python-hyper/hpack/releases/tag/v4.2.0","source":"GitHub Advisory Database"},{"url":"https://github.com/advisories/GHSA-8v8h-hg4w-mvq2","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-09-24T13:24:31.887152Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"vendor and product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-01T17:55:38.238084125Z","content_hash":"67a684e3e4c96fa7b537090f94732ea03735582aac81ceac2f155aef6139c7ed"}}