CVE-2026-104183

MEDIUMPre-NVD 5.15.1
EchelonGraph scoreHIGH confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 5.1 from GitHub Security Advisory (severity: MODERATE) published 2026-10-05. A secondary CVSS source baseline 5.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-91057 (ENISA EUVD) · GHSA-mjw6-4jj6-33hc (GitHub Security Advisories)Source: ENISA EUVD

5.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
5.1
EG Score
5.1MEDIUMhigh confidence
EG Risk
39
EG Risk 39/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity51% × 45%
Impact severity (EG Severity): CVSS 5.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
9th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.1): severity, escalated by confirmed exploitation. This CVE's 5.1 is its impact severity (EG Severity), not escalated.

EG Severity
5.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 1, 2026

Last Modified

October 2, 2026

Advisory Details (2)

Auto-updated Oct 1, 2026
Patch available. Sources: github_commit, github.
GitHub commit

commit 2f2d35bbb547 (uhop/stream-json)

Fix landed in uhop/stream-json commit 2f2d35bbb547 — awaiting tagged release

https://github.com/uhop/stream-json/commit/2f2d35bbb547306991ded6487a279154d865a358
GitHub advisoryMentions a patch (unverified)

Prototype pollution: Assembler writes this.current[this.key] on plain objects · Advisory · uhop/stream-json · GitHub

https://github.com/uhop/stream-json/security/advisories/GHSA-mjw6-4jj6-33hc

Vendor Advisories for CVE-2026-104183(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
npmstream-json @ 3.6.0 (fixes < 3.6.0)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFix by version rangeDependents
stream-json—
  • every version up to 3.6.0: fixed in 3.6.0
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 44× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  2. 2026-11-01 08:00 UTCGHSA enrichmentGHSA-mjw6-4jj6-33hc · GitHub severity MODERATE · GitHub CVSS 5.1
  3. 2026-11-01 08:00 UTCEG score recompute
  4. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  5. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  6. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  7. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  8. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  9. 2026-10-27 09:55 UTCOSV refresh
  10. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  11. 2026-10-25 14:56 UTCEG score recompute
  12. 2026-10-24 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  13. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  14. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  15. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  16. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  17. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  18. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  19. 2026-10-18 05:09 UTCEG score recompute
  20. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  21. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  22. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  23. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  24. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  25. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 8th percentile
Show 24 more
  1. 2026-10-12 16:10 UTCEG score recompute
  2. 2026-10-11 20:15 UTCEG score recompute
  3. 2026-10-11 18:27 UTCEG score recompute
  4. 2026-10-11 15:01 UTCEG score recompute
  5. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  6. 2026-10-11 09:33 UTCEG score recompute
  7. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  8. 2026-10-10 07:36 UTCEG score recompute
  9. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  10. 2026-10-09 05:48 UTCEG score recompute
  11. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  12. 2026-10-08 03:59 UTCEG score recompute
  13. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  14. 2026-10-07 02:10 UTCEG score recompute
  15. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  16. 2026-10-06 00:21 UTCEG score recompute
  17. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  18. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  19. 2026-10-03 20:43 UTCEG score recompute
  20. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  21. 2026-10-02 18:51 UTCEG score recompute
  22. 2026-10-01 21:20 UTCEG score recompute
  23. 2026-10-01 20:22 UTCEG score recomputeFirst assessed: 5.1 MEDIUM
  24. 2026-10-01 20:20 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-104183?
CVE-2026-104183 is a medium-severity vulnerability; its CVE record was published on October 1, 2026. 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…
When was the CVE record for CVE-2026-104183 published?
The CVE record for CVE-2026-104183 was published on October 1, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 2, 2026; the record at its source may have been updated since.
Is CVE-2026-104183 actively exploited?
CVE-2026-104183 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-104183?
CVE-2026-104183 has a CVSS base score of 5.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-104183?
A fix for CVE-2026-104183 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-104183 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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