CVE-2026-59152 LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform

Description

LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to 0.8.18, an attacker who can send an HTTP request to a server running the LangSmith SDK's TracingMiddleware can cause that server to read an arbitrary file from its local filesystem and upload the contents to LangSmith as a trace attachment. Depending on how the distributed trace system is deployed, triggering a read may not require authentication. Retrieving the contents requires read access to the LangSmith workspace the traces are sent to. The net effect is a trust-boundary crossing: a party with workspace trace-read access (for example a low-privilege workspace member, a contractor, or a compromised teammate account) gains the ability to read files from any server running TracingMiddleware, a capability outside that workspace's intended trust boundary. This vulnerability is fixed in 0.8.18.

Affected products and versions