Is CVE-2026-40190 in the CISA KEV catalog?

No. CVE-2026-40190 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40190?

CVE-2026-40190 has a CVSS v3 base score of 5.6 (MEDIUM).

What is the EPSS score for CVE-2026-40190?

CVE-2026-40190 has an EPSS score of 0.23% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-40190?

No published fix for CVE-2026-40190 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-40190

MEDIUM

5.6

CVSS v3

NVD

Description

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.

CWE-1321

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityLow

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploit Intelligence

0.23%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Other references1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-29.