Deserialization in Langchain-Ai Langsmith-Sdk

CVE-2026-45134

LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to LangSmith SDK Python 0.8.0 and JS/TS 0.6.0, the LangSmith SDK's prompt pull methods (pull_prompt / pull_prompt_commit in Python, pullPrompt / pullPromptCommit in JS/TS) fetch and deserialize prompt manifests from the LangSmith Hub. These manifests may contain serialized LangChain objects and model configuration that affect runtime behavior. When pulling a public prompt by owner/name identifier, the manifest content is controlled by an external party, but prior versions of the SDK did not distinguish this from pulling a prompt within the caller's own organization. This vulnerability is fixed in LangSmith SDK Python 0.8.0 and JS/TS 0.6.0.

Vulnerability class: Insecure Deserialization

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-45134: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-45134?
CVE-2026-45134 is a high-severity vulnerability in Langchain-Ai Langsmith-Sdk, classified under Deserialization of Untrusted Data. CVSS score: 7.1/10. Published 2026-05-27.
How severe is CVE-2026-45134?
High severity. CVSS v3 base score is 7.1 out of 10.