CVE-2026-40190

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.3% (25th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 5.6 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-04-10) is not newer than that change (2026-10-26), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated

Also known asEUVD-2026-21594 (ENISA EUVD) · GHSA-fw9q-39r9-c252 (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
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: 0.3%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to 0.5.18, the LangSmith JavaScript/TypeScript SDK (langsmith) contains an incomplete prototype pollution fix in its internally vendored lodash set() utility. The baseAssignValue() function only guards against the __proto__ key, but fails to prevent traversal via constructor.prototype. This allows an attacker who controls keys in data processed by the createAnonymizer() API to pollute Object.prototype, affecting all objects in the Node.js process. This vulnerability is fixed in 0.5.18.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 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
0.3%
EPSS %ILE
25th
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). 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

April 10, 2026

Last Modified

October 26, 2026

Advisory Details (1)

Auto-updated Nov 7, 2026
🔬 Proof of concept available. Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)🟡 PoC Available

Prototype Pollution in langsmith-sdk via Incomplete `__proto__` Guard in Internal lodash `set()` · Advisory · langchain-ai/langsmith-sdk · GitHub

Affected: 0.5.18

https://github.com/langchain-ai/langsmith-sdk/security/advisories/GHSA-fw9q-39r9-c252

Vendor Advisories for CVE-2026-40190(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
npmlangsmith @ 0.5.18 (fixes <= 0.5.17)—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
langsmith—
  • every version up to 0.5.18: fixed in 0.5.18
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 43× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 255 rows on record for this CVE, as 99 entries (1 repeat merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 155 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 00:35 UTCEchelonGraph re-scored
  2. 2026-11-13 00:35 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  3. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  4. 2026-11-12 00:25 UTCEchelonGraph re-scored
  5. 2026-11-12 00:25 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  6. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  7. 2026-11-11 00:14 UTCEchelonGraph re-scored
  8. 2026-11-11 00:14 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  9. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  10. 2026-11-10 00:03 UTCEchelonGraph re-scored
  11. 2026-11-10 00:03 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  12. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-11-08 23:53 UTCEchelonGraph re-scored
  14. 2026-11-08 23:53 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  15. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-11-07 23:42 UTCEchelonGraph re-scored
  17. 2026-11-07 23:42 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  18. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-11-06 23:31 UTCEchelonGraph re-scored
  20. 2026-11-06 23:31 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  21. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  22. 2026-11-05 23:21 UTCEchelonGraph re-scored
  23. 2026-11-05 23:21 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  24. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  25. 2026-11-04 23:11 UTCEchelonGraph re-scored
Show 74 more
  1. 2026-11-04 23:11 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  2. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  3. 2026-11-03 23:00 UTCEchelonGraph re-scored
  4. 2026-11-03 23:00 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  5. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  6. 2026-11-02 22:49 UTCEchelonGraph re-scored
  7. 2026-11-02 22:49 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  8. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  9. 2026-11-01 22:38 UTCEchelonGraph re-scored
  10. 2026-11-01 22:38 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  11. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  12. 2026-11-01 07:52 UTCGHSA enrichmentGHSA-fw9q-39r9-c252 · GitHub severity MODERATE · GitHub CVSS 5.6
  13. 2026-11-01 07:52 UTCEchelonGraph re-scored
  14. 2026-10-31 22:29 UTCEchelonGraph re-scored
  15. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  16. 2026-10-30 22:18 UTCEchelonGraph re-scored
  17. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  18. 2026-10-29 22:04 UTCEchelonGraph re-scored
  19. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  20. 2026-10-28 21:52 UTCEchelonGraph re-scored
  21. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  22. 2026-10-27 21:42 UTCEchelonGraph re-scored
  23. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  24. 2026-10-26 21:27 UTCEchelonGraph re-scored
  25. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  26. 2026-10-25 22:58 UTCEchelonGraph re-scored
  27. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  28. 2026-10-25 14:31 UTCEchelonGraph re-scored
  29. 2026-10-24 22:46 UTCEchelonGraph re-scored
  30. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  31. 2026-10-23 22:36 UTCEchelonGraph re-scored
  32. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  33. 2026-10-22 22:13 UTCEchelonGraph re-scored
  34. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  35. 2026-10-21 21:49 UTCEchelonGraph re-scored
  36. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  37. 2026-10-20 21:09 UTCEchelonGraph re-scored
  38. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  39. 2026-10-19 20:58 UTCEchelonGraph re-scored
  40. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  41. 2026-10-18 19:13 UTCEchelonGraph re-scored
  42. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  43. 2026-10-18 03:43 UTCEchelonGraph re-scored
  44. 2026-10-17 19:02 UTCEchelonGraph re-scored
  45. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  46. 2026-10-16 18:51 UTCEchelonGraph re-scored
  47. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  48. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  49. 2026-10-15 15:52 UTCEchelonGraph re-scored
  50. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  51. 2026-10-14 10:04 UTCEchelonGraph re-scored
  52. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  53. 2026-10-13 08:18 UTCEchelonGraph re-scored
  54. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  55. 2026-10-12 16:09 UTCEchelonGraph re-scored
  56. 2026-10-11 19:52 UTCEchelonGraph re-scored
  57. 2026-10-11 17:05 UTCEchelonGraph re-scored
  58. 2026-10-11 14:31 UTCEchelonGraph re-scored
  59. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  60. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  61. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  62. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  63. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  64. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  65. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  66. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  67. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  68. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  69. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  70. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  71. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  72. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  73. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  74. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 24th percentile

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Frequently asked(5)

What is CVE-2026-40190?
CVE-2026-40190 is a critical-severity vulnerability; its CVE record was published on April 10, 2026. LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to 0.5.18, the LangSmith JavaScript/TypeScript SDK (langsmith) contains an incomplete prototype pollution fix in its internally vendored lodash set() utility. The baseAssignValue() function only guards against…
When was the CVE record for CVE-2026-40190 published?
The CVE record for CVE-2026-40190 was published on April 10, 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 26, 2026; the record at its source may have been updated since.
Is CVE-2026-40190 actively exploited?
CVE-2026-40190 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40190?
CVE-2026-40190 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-40190?
A fix for CVE-2026-40190 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-40190 are linked in the Vendor Advisories panel on this page.

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