{"id":"CVE-2026-54901","aliases":["DEBIAN-CVE-2026-54901","EUVD-2026-40856","GHSA-vwm4-62gf-x745","UBUNTU-CVE-2026-54901"],"status":"published","title":"Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","severity":{"version":"4.0","score":6.3,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00407,"percentile":0.35259,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-416"],"published":"2026-06-19T20:47:25Z","modified":"2026-10-26T11:47:35Z","fixes":[{"ecosystem":"RubyGems","package":"oj","fixed_in":["3.17.2","3.17.3"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:12","package":"ruby-oj","fixed_in":["3.14.2-1+deb12u1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"ruby-oj","fixed_in":["3.16.3-1+deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"ruby-oj","fixed_in":["3.17.3-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.17.2"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.14.2-1+deb12u1"}]}],"versions":["3.14.2-1"]},{"source":"osv","ecosystem":"Debian:13","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.16.3-1+deb13u1"}]}],"versions":["3.16.3-1"]},{"source":"osv","ecosystem":"Debian:14","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.17.3-1"}]}],"versions":["3.16.12-1","3.16.15-1","3.16.16-1","3.16.3-1","3.17.0-1","3.17.1-1"]},{"source":"osv","ecosystem":"RubyGems","package":"oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.17.3"}]}],"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"]},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.10-1","2.1.4-1","2.4.0-1","2.5.3-1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.12.10-3","2.12.10-3build1","2.12.10-4","2.12.10-4build1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.17.4-1","3.4.0-1","3.4.0-1build1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.8.1-1","3.9.1-1","3.9.2-1","3.10.1-1","3.10.1-1build1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.11.0-1","3.13.7-1","3.13.7-1build1","3.13.9-1","3.13.9-1build1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.15.0-1","3.16.1-1","3.16.3-1","3.16.3-1build1","3.16.3-1build2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.16.3-1build3"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.16.15-1","3.17.0-1","3.17.1-1","3.17.3-1","3.17.4-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"ruby-oj","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.16.3-1build3","3.16.12-1","3.16.15-1"]}],"products":[{"vendor":"ohler55","product":"oj"}],"references":[{"url":"https://github.com/ohler55/oj/security/advisories/GHSA-vwm4-62gf-x745","tags":["x_refsource_CONFIRM","exploit","web","report"]},{"url":"https://github.com/advisories/GHSA-vwm4-62gf-x745"},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-54901","tags":["advisory"]},{"url":"https://github.com/ohler55/oj","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-54901","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-54901","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-54901","title":"Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","status":"published","published":"2026-06-30T23:36:38.526Z","modified":"2026-07-01T12:34:23.576Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T13:37:58.613221Z"}],"euvd":[{"id":"EUVD-2026-40856","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","status":"published","published":"2026-06-30T23:36:38Z","modified":"2026-07-01T12:34:23Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T18:20:20.297775Z"}],"ghsa":[{"id":"GHSA-vwm4-62gf-x745","title":"Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking","description":"### Summary\n\n`Oj::Parser` in usual mode does not mark `array_class` and `hash_class` references during garbage collection. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent `parse` call dereferences the freed object, producing a segfault.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/usual.c` / `ext/oj/parser.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\nThe `parser_mark` function in `ext/oj/parser.c` is registered as the GC mark callback for the parser's `TypedData`. If `array_class` (stored as `d-\u003earray_class` in the `Usual` struct) is not passed to `rb_gc_mark`, the GC does not know it is referenced and may collect it.\n\nWhen `close_array_class` (`usual.c:405`) later calls `rb_funcallv` on the collected class VALUE, it accesses freed memory, crashing at `RIP: 0x7f... / 0x0000000000000000`.\n\nCrash output:\n```\narray_class finalized\nabout to parse\n[BUG] Segmentation fault at 0x0000000000000000\n    close_array_class+0x194  /ext/oj/usual.c:405\n    parse+0x17b3             /ext/oj/parser.c:715\n    parser_parse+0x10b       /ext/oj/parser.c:1408\nRIP: 0x7fd1b46d68b7  RBP: 0x0000000000000000\n```\n\n### Reproduce\n\n```ruby\nrequire 'oj'\np = Oj::Parser.new(:usual,\n  array_class: (ac = Class.new { def \u003c\u003c(_x); end }))\nObjectSpace.define_finalizer(ac, proc { warn 'array_class finalized' })\nac = nil\nGC.start(full_mark: true, immediate_sweep: true)  # collect the class\np.parse('[1]')  # segfault\n```","status":"published","published":"2026-06-19T20:47:25Z","modified":"2026-06-19T20:47:26Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:40:31.656952Z"}],"nvd":[{"id":"CVE-2026-54901","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:33.467Z","modified":"2026-10-25T17:10:00.197Z","cvss":[{"version":"4.0","score":6.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:12:27.199837Z"}],"osv":[{"id":"DEBIAN-CVE-2026-54901","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:33.467Z","modified":"2026-10-26T11:47:35.180936852Z","cvss":[{"version":"4.0","score":6.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"updated_at":"2026-11-02T15:45:57.236551Z"},{"id":"GHSA-vwm4-62gf-x745","title":"Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking","description":"### Summary\n\n`Oj::Parser` in usual mode does not mark `array_class` and `hash_class` references during garbage collection. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent `parse` call dereferences the freed object, producing a segfault.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/usual.c` / `ext/oj/parser.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\nThe `parser_mark` function in `ext/oj/parser.c` is registered as the GC mark callback for the parser's `TypedData`. If `array_class` (stored as `d-\u003earray_class` in the `Usual` struct) is not passed to `rb_gc_mark`, the GC does not know it is referenced and may collect it.\n\nWhen `close_array_class` (`usual.c:405`) later calls `rb_funcallv` on the collected class VALUE, it accesses freed memory, crashing at `RIP: 0x7f... / 0x0000000000000000`.\n\nCrash output:\n```\narray_class finalized\nabout to parse\n[BUG] Segmentation fault at 0x0000000000000000\n    close_array_class+0x194  /ext/oj/usual.c:405\n    parse+0x17b3             /ext/oj/parser.c:715\n    parser_parse+0x10b       /ext/oj/parser.c:1408\nRIP: 0x7fd1b46d68b7  RBP: 0x0000000000000000\n```\n\n### Reproduce\n\n```ruby\nrequire 'oj'\np = Oj::Parser.new(:usual,\n  array_class: (ac = Class.new { def \u003c\u003c(_x); end }))\nObjectSpace.define_finalizer(ac, proc { warn 'array_class finalized' })\nac = nil\nGC.start(full_mark: true, immediate_sweep: true)  # collect the class\np.parse('[1]')  # segfault\n```","status":"published","published":"2026-06-19T20:47:25Z","modified":"2026-09-10T03:50:12.35562778Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T15:46:57.694388Z"},{"id":"UBUNTU-CVE-2026-54901","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:00Z","modified":"2026-10-17T13:00:26.302962284Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T16:56:41.382716Z"}]}}