{"id":"CVE-2026-71847","summary":"Ruby JSON: JSON::ResumableParser#partial_value dereferences a freed input buffer and crashes on truncated duplicate-key streams","details":"Ruby JSON is a JSON implementation for Ruby. From 2.20.0 until 2.21.2, Ruby's JSON native C extension clears the consumed JSON::ResumableParser input buffer but leaves state.start, state.cursor, and state.end pointing into released storage. When partial_value reconstructs an incomplete object containing duplicate keys, the duplicate-key warning path calls cursor_position, which dereferences those stale pointers. This results in a heap-use-after-free and can terminate the Ruby process. An attacker who can supply JSON stream data to an application using JSON::ResumableParser may cause process termination when the application calls partial_value on incomplete attacker-controlled input containing duplicate object keys. This issue has been fixed in version 2.21.2.","aliases":["GHSA-9hj4-r449-hfvc"],"modified":"2026-08-09T03:30:31.875664325Z","published":"2026-08-07T18:31:28.507Z","related":["CGA-8h37-7mm8-c7q6"],"database_specific":{"cwe_ids":["CWE-416"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71847.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71847.json"},{"type":"ADVISORY","url":"https://github.com/ruby/json/security/advisories/GHSA-9hj4-r449-hfvc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-71847"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ruby/json","events":[{"introduced":"13162921b89c4f662aa018771403457f069f7e26"},{"fixed":"5a32e4367ca5976f62af12887a09685b7109b054"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"2.20.0"},{"fixed":"2.21.2"}]}}],"versions":["v2.21.1","v2.21.0","v2.20.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-71847.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}