{"affected":[{"database_specific":{"last_known_affected_version_range":"< 3.17.2","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-9ppp-w3g4-fh4q/GHSA-9ppp-w3g4-fh4q.json"},"package":{"ecosystem":"RubyGems","name":"oj","purl":"pkg:gem/oj"},"ranges":[{"events":[{"introduced":"0"},{"fixed":"3.17.3"}],"type":"ECOSYSTEM"}],"versions":["0.5","0.5.1","0.5.2","0.6.0","0.7.0","0.8.0","0.9.0","1.0.0","1.0.1","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.1.0","1.1.1","1.2.0","1.2.1","1.2.10","1.2.11","1.2.12","1.2.13","1.2.2","1.2.3","1.2.4","1.2.5","1.2.6","1.2.7","1.2.8","1.2.9","1.3.0","1.3.2","1.3.4","1.3.5","1.3.6","1.3.7","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4.6a2","1.4.7","2.0.0","2.0.1","2.0.10","2.0.11","2.0.12","2.0.13","2.0.14","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.0.8","2.0.9","2.1.0","2.1.1","2.1.2","2.1.3","2.1.4","2.1.6","2.1.7","2.10.0","2.10.1","2.10.2","2.10.3","2.10.4","2.11.0","2.11.1","2.11.2","2.11.3","2.11.4","2.11.5","2.12.0","2.12.1","2.12.10","2.12.11","2.12.12","2.12.13","2.12.14","2.12.2","2.12.3","2.12.4","2.12.5","2.12.6","2.12.7","2.12.8","2.12.9","2.13.0","2.13.1","2.14.0","2.14.1","2.14.2","2.14.3","2.14.4","2.14.5","2.14.6","2.15.0","2.15.1","2.16.0","2.16.1","2.17.0","2.17.1","2.17.2","2.17.3","2.17.4","2.17.5","2.18.0","2.18.1","2.18.2","2.18.3","2.18.4","2.18.5","2.2.0","2.2.1","2.2.2","2.2.3","2.3.0","2.4.0","2.4.1","2.4.2","2.4.3","2.5.1","2.5.2","2.5.3","2.5.4","2.5.5","2.6.0","2.6.1","2.7.0","2.7.1","2.7.2","2.7.3","2.8.0","2.8.1","2.9.0","2.9.1","2.9.2","2.9.3","2.9.4","2.9.5","2.9.6","2.9.7","2.9.8","2.9.9","3.0.0","3.0.1","3.0.10","3.0.11","3.0.2","3.0.3","3.0.4","3.0.5","3.0.6","3.0.7","3.0.8","3.0.9","3.1.0","3.1.2","3.1.3","3.1.4","3.10.0","3.10.1","3.10.10","3.10.11","3.10.12","3.10.13","3.10.14","3.10.15","3.10.16","3.10.17","3.10.18","3.10.2","3.10.3","3.10.5","3.10.6","3.10.7","3.10.8","3.10.9","3.11.0","3.11.1","3.11.2","3.11.3","3.11.4","3.11.5","3.11.6","3.11.7","3.11.8","3.12.0","3.12.1","3.12.2","3.12.3","3.13.0","3.13.1","3.13.10","3.13.11","3.13.12","3.13.13","3.13.14","3.13.15","3.13.16","3.13.17","3.13.18","3.13.19","3.13.2","3.13.20","3.13.21","3.13.22","3.13.23","3.13.3","3.13.4","3.13.5","3.13.6","3.13.7","3.13.8","3.13.9","3.14.0","3.14.1","3.14.2","3.14.3","3.15.0","3.15.1","3.16.0","3.16.1","3.16.10","3.16.11","3.16.12","3.16.13","3.16.14","3.16.15","3.16.16","3.16.17","3.16.2","3.16.3","3.16.4","3.16.5","3.16.6","3.16.7","3.16.8","3.16.9","3.17.0","3.17.1","3.2.0","3.2.1","3.3.0","3.3.1","3.3.10","3.3.2","3.3.3","3.3.4","3.3.5","3.3.6","3.3.7","3.3.8","3.3.9","3.4.0","3.5.0","3.5.1","3.6.0","3.6.10","3.6.11","3.6.12","3.6.13","3.6.2","3.6.3","3.6.4","3.6.5","3.6.6","3.6.7","3.6.8","3.6.9","3.7.0","3.7.1","3.7.10","3.7.11","3.7.12","3.7.2","3.7.3","3.7.4","3.7.5","3.7.6","3.7.7","3.7.8","3.7.9","3.8.0","3.8.1","3.9.0","3.9.1","3.9.2"]}],"aliases":["CVE-2026-54897"],"database_specific":{"cwe_ids":["CWE-416"],"github_reviewed":true,"github_reviewed_at":"2026-06-19T19:36:50Z","nvd_published_at":null,"severity":"HIGH"},"details":"### Summary\n\n`Oj::Doc` iterators (`each_value`, `each_child`, `each_leaf`) are vulnerable to a heap use-after-free. When a Ruby block yielded during iteration calls `doc.close` or `d.close`, the document's heap memory is freed while the C iterator is still running. When control returns from the block, the iterator reads from the freed region, producing a use-after-free accessible from pure Ruby.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/fast.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\nThe iterators in `ext/oj/fast.c` follow the pattern:\n\n```c\n// fast.c:1505 (doc_each_child)\nstatic VALUE doc_each_child(VALUE self, ...) {\n    ...\n    while (cur != NULL) {\n        rb_yield(...);       // ← Ruby block executes here\n        cur = cur->next;     // ← cur is now freed if block called close()\n    }\n}\n```\n\n`rb_yield` can invoke arbitrary Ruby code, including calling `close()` on the `Doc` or any child node, which calls `ruby_sized_xfree` on the backing buffer. On return, the C code reads `cur->next` from the freed region. All three iterators are affected.\n\nASAN report (each_child variant):\n```\n==253632==ERROR: AddressSanitizer: heap-use-after-free on address 0x5210000bd080\nREAD of size 8 at 0x5210000bd080 thread T0\n    #0 doc_each_child  /ext/oj/fast.c:1505\n0x5210000bd080 is located 896 bytes inside of 4064-byte region [0x5210000bcd00, 0x5210000bdce0)\nfreed by thread T0 here:\n    #0 free\n    #1 ruby_sized_xfree  (libruby-3.3.so.3.3)\n```\n\nAll three iterators trigger the same freed region (`fd` shadow bytes):\n```\n0x5210000bd080:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd\n```\n\n### Reproduce\n\n```ruby\nrequire 'oj'\n# each_child\nOj::Doc.open('[1,2]') { |doc| doc.each_child { |d| d.close } }\n# each_value\nOj::Doc.open('[1,2]') { |doc| doc.each_value { |v| doc.close } }\n# each_leaf\nOj::Doc.open('[1,[2]]') { |doc| doc.each_leaf { |d| d.close } }\n```","id":"GHSA-9ppp-w3g4-fh4q","modified":"2026-09-10T03:51:08.386798324Z","published":"2026-06-19T19:36:50Z","references":[{"type":"WEB","url":"https://github.com/ohler55/oj/security/advisories/GHSA-9ppp-w3g4-fh4q"},{"type":"PACKAGE","url":"https://github.com/ohler55/oj"}],"schema_version":"1.9.0","severity":[{"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","type":"CVSS_V4"}],"summary":"Oj: Use-After-Free in Oj::Doc Iterators via Reentrant Close"}