{"id":"GHSA-35w3-pjm6-wj95","summary":"Oj: Heap Buffer Overflow in Oj.dump Exception Serialization via Large Indent","details":"### Summary\n\n`Oj.dump` in object mode is vulnerable to a heap buffer overflow when serializing Exception objects with a large `:indent` value. The serializer allocates a buffer sized for the object's attributes but does not account for the indent bytes added on each write. With `indent: 5000`, the accumulation of 5,000-byte indent strings overflows the 13,150-byte heap allocation, corrupting adjacent heap memory.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/dump.h`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\n`ext/oj/dump.h`, line 75–77:\n\n```c\nstatic void fill_indent(Out out, int depth) {\n    if (0 \u003c out-\u003eopts-\u003eindent) {\n        memset(out-\u003ebuf + out-\u003ecur, ' ', (size_t)(out-\u003eopts-\u003eindent * depth));\n```\n\nWhen dumping an Exception object in `:object` mode, `dump_obj_attrs` calls `fill_indent` repeatedly for each attribute. The buffer is pre-allocated based on the serialized content but not the indentation overhead. With `indent: 5000` the indent block for a nested object exceeds the remaining buffer space, producing a heap-buffer-overflow of size 5,000 at the end of the allocated region.\n\nASAN report:\n```\n==101656==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x527000022c5e\nWRITE of size 5000 at 0x527000022c5e thread T0\n    #0 memset\n    #1 fill_indent       /ext/oj/dump.h:77\n    #2 dump_obj_attrs    /ext/oj/dump_object.c:552\n    #3 dump_obj          /ext/oj/dump_object.c:80\n    #4 oj_dump_obj_val   /ext/oj/dump_object.c:708\n    #5 oj_dump_obj_to_json_using_params  /ext/oj/dump.c:817\n    #6 dump_body         /ext/oj/oj.c:1429\n    #7 dump              /ext/oj/oj.c:1480\n0x527000022c5e is located 0 bytes after 13150-byte region [0x52700001f900, 0x527000022c5e)\n```\n\n### Reproduce\n\n```ruby\nrequire \"oj\"\nobj = Oj.load('{\"^o\":\"RuntimeError\"}', mode: :object)\nOj.dump(obj, mode: :object, indent: 5000)\n```\n\n### Workarounds\n\nThis is at the discretion of the developer and not a public facing option so the workaround is the develop should not use extreme indents and should not offer the option for users to dump Ruby data with unlimited indentation size.","aliases":["CVE-2026-54896"],"modified":"2026-07-17T21:11:11.247591162Z","published":"2026-06-19T19:36:47Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-122"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-06-19T19:36:47Z"},"references":[{"type":"WEB","url":"https://github.com/ohler55/oj/security/advisories/GHSA-35w3-pjm6-wj95"},{"type":"PACKAGE","url":"https://github.com/ohler55/oj"}],"affected":[{"package":{"name":"oj","ecosystem":"RubyGems","purl":"pkg:gem/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"],"database_specific":{"last_known_affected_version_range":"\u003c 3.17.2","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-35w3-pjm6-wj95/GHSA-35w3-pjm6-wj95.json"}}],"schema_version":"1.9.0","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"}]}