{"id":"GHSA-7rx3-28cr-v5wh","revision":null,"records":[{"revision":"178a2d02bdc54821856fce710edcf131","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-7rx3-28cr-v5wh","aliases":[],"title":"Handlebars.js has a Prototype Method Access Control Gap via Missing __lookupSetter__ Blocklist Entry","description":"## Summary\n\nThe prototype method blocklist in `lib/handlebars/internal/proto-access.js` blocks `constructor`, `__defineGetter__`, `__defineSetter__`, and `__lookupGetter__`, but omits the symmetric `__lookupSetter__`. This omission is only exploitable when the non-default runtime option `allowProtoMethodsByDefault: true` is explicitly set — in that configuration `__lookupSetter__` becomes accessible while its counterparts remain blocked, creating an inconsistent security boundary.\n\n`4.6.0` is the version that introduced `protoAccessControl` and the `allowProtoMethodsByDefault` runtime option.\n\n## Description\n\nIn `lib/handlebars/internal/proto-access.js`:\n\n```javascript\nconst methodWhiteList = Object.create(null);\nmethodWhiteList['constructor']      = false;\nmethodWhiteList['__defineGetter__'] = false;\nmethodWhiteList['__defineSetter__'] = false;\nmethodWhiteList['__lookupGetter__'] = false;\n// __lookupSetter__ intentionally blocked in CVE-2021-23383,\n// but omitted here — creating an asymmetric blocklist\n```\n\nAll four legacy accessor helpers (`__defineGetter__`, `__defineSetter__`, `__lookupGetter__`, `__lookupSetter__`) were involved in the exploit chain addressed by CVE-2021-23383. Three of the four were explicitly blocked; `__lookupSetter__` was left out.\n\nWhen `allowProtoMethodsByDefault: true` is set, any prototype method **not present** in `methodWhiteList` is permitted by default. Because `__lookupSetter__` is absent from the list, it passes the `checkWhiteList` check and is accessible in templates, while `__lookupGetter__` (its sibling) is correctly denied.\n\n## Workarounds\n\n- Do **not** set `allowProtoMethodsByDefault: true`. The default configuration is not affected.\n- If `allowProtoMethodsByDefault` must be enabled, ensure templates do not reference  `__lookupSetter__` through untrusted input.","state":0,"publishedAt":"2026-03-29T15:17:15+00:00","modifiedAt":"2026-09-10T03:50:38.0841326+00:00","affected":[{"ecosystem":"npm","name":"handlebars","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"4.6.0"},{"kind":"fixed","version":"4.7.9"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-7rx3-28cr-v5wh","https://github.com/advisories/GHSA-765h-qjxv-5f44","https://github.com/handlebars-lang/handlebars.js","https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"],"sourceUrl":"https://github.com/advisories/GHSA-7rx3-28cr-v5wh","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-7rx3-28cr-v5wh","identifiers":["GHSA-7rx3-28cr-v5wh"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-15T10:02:17.3763497+00:00","complete":true,"records":1781,"lastAttemptAt":"2026-11-15T10:02:17.3763497+00:00","lastSuccessAt":"2026-11-15T10:02:17.6058686+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:17.6058701+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-7de4d7559a5263003f03d9f70577ab06f92ba4178309f26fce53e22a4a959294-3113592d787b958ba87cf6300a2f439f8836169d49c36cdd65ca959c60a1acfe","complete":true,"records":425784,"lastAttemptAt":"2026-11-15T10:02:16.903149+00:00","lastSuccessAt":"2026-11-15T10:02:16.8893294+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:16.903149+00:00","snapshotPublishedAt":"2026-11-15T09:28:12+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-ab7e83ec40d841f68d6d65c6dcc2aa85","complete":false,"records":13821,"lastAttemptAt":"2026-11-15T10:12:45.3805188+00:00","lastSuccessAt":"2026-11-15T10:12:45.374+00:00","error":"158 identifier lookups failed; latest failures include AccessDenied (HTTP 403). Other identifiers were checked independently.","lastVerifiedAt":"2026-11-15T10:12:45.374+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13573,"expectedIdentifiers":13874,"failedIdentifiers":158},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-15T10:02:17.3763497+00:00","complete":true,"records":1125,"lastAttemptAt":"2026-11-15T10:02:17.3763497+00:00","lastSuccessAt":"2026-11-15T10:02:17.760821+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:17.7608224+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-d33b5144615b488f88b7a7390696bc39","complete":true,"records":13833,"lastAttemptAt":"2026-11-15T10:02:36.0431422+00:00","lastSuccessAt":"2026-11-15T10:02:36.038+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:36.038+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13874,"expectedIdentifiers":13874,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-64eea06dbd27de8464d5dbce1b78cc794cc59e2d901516ae0d3ea76e624cdae0","complete":true,"records":9955,"lastAttemptAt":"2026-11-15T10:02:17.2383659+00:00","lastSuccessAt":"2026-11-14T13:57:23.1208135+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:17.2383659+00:00","snapshotPublishedAt":"2026-11-14T13:17:57+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-f4424d7d4861b1af1404bd15abcb83f295dcd003412a9340ca99dc8200aa148a","complete":true,"records":2014,"lastAttemptAt":"2026-11-15T10:02:16.9649371+00:00","lastSuccessAt":"2026-11-13T19:57:08.2864435+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:16.9649371+00:00","snapshotPublishedAt":"2026-11-13T19:33:10+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-012aff9b2fb349d53e2c4bace6ca57956b6f5f9d82c1dc9fdc1c9b3c738f8977","complete":true,"records":3148,"lastAttemptAt":"2026-11-15T10:02:17.2553329+00:00","lastSuccessAt":"2026-11-14T04:57:03.8279646+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:17.2553329+00:00","snapshotPublishedAt":"2026-11-14T03:02:50+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-878f718ccd076f540460423958c8e379b139b997b45858275573ecc4d702fe9a","complete":true,"records":232474,"lastAttemptAt":"2026-11-15T10:02:17.1321415+00:00","lastSuccessAt":"2026-11-15T05:33:06.8241102+00:00","error":null,"lastVerifiedAt":"2026-11-15T10:02:17.1321415+00:00","snapshotPublishedAt":"2026-11-15T04:33:08+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}