Vulnerability in stream-json (CVE-2026-104183)
Summary
Vulnerability in stream-json (CVE-2026-104183). Risk of unauthorized operations or information disclosure. Exploitable via __proto__. Mitigation: upgrade to 3.6.0 or later.
Original description
The description as published by the source.
Summary
A prototype-pollution vulnerability in stream-json lets attacker-controlled JSON replace a parsed object's prototype.
Details
The 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.
PoC
Run:
node poc-stream-json-proto-injection.mjs
Full proof-of-concept source (poc-stream-json-proto-injection.mjs):
// stream-json v3.5.0 (npm latest) — local [[Prototype]] replacement via `__proto__` keys
// Class: prototype injection in a JSON deserializer (jsonparse/bser/jsonc-parser/plist family)
// Root cause: Assembler builds every object as a plain `Object` and writes
// `this.current[this.key] = value` (src/core/assembler.js:160,180 — plain assignment,
// ToPropertyKey → inherited Object.prototype __proto__ setter fires)
// Spec baseline: JSON.parse (CreateDataProperty) → own data property, no prototype change
// Run: node poc-stream-json-proto-injection.mjs (from C:/Users/rncb0/AppData/Local/Temp/0day/sj-lab)
import { parser } from 'stream-json';
import jsoncParser from 'stream-json/jsonc/Parser.js';
import { streamValues } from 'stream-json/streamers/stream-values.js';
import { streamObject } from 'stream-json/streamers/stream-object.js';
import { Readable } from '…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-104183 has been found in stream-json.
Attackers can target a specific entry point like __proto__ over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.1/10.
What to do: upgrade stream-json to 3.6.0 or later.
If unsure, ask your IT team or search "stream-json CVE-2026-104183" on the vendor's site.
CVE-2026-104183 (stream-json) — CWE-1321 / CVSS v3 5.1
Attack vector: local / unauthenticated / no user interaction
Attack surface: __proto__ / Object / Object.prototype / Assembler
Patched: 3.6.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-1321) exists in stream-json. Attackers reach the vulnerable code path via __proto__ without authentication.
Check the vendor advisory for the affected versions of stream-json. Attack surface: __proto__ / Object / Object.prototype / Assembler.
Severity: Medium (CVSS 5.1/10). Risk of unauthorized operations or information disclosure.
Update to 3.6.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'stream-json' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'stream-json' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
stream-jsonを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade stream-json to 3.6.0ステージング環境で 3.6.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web github.com
- web github.com
- web nvd.nist.gov
- web github.com