CVE-2026-59152: Arbitrary server-side file read in LangSmith SDK TracingMiddleware
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
LangSmith SDK TracingMiddlewareto a version that resolves this vulnerability.Fixed in 0.8.18
Event History
Frequently Asked Questions
What is the severity of CVE-2026-59152?
CVE-2026-59152 has a medium severity rating of 5.
How do I fix CVE-2026-59152?
To fix CVE-2026-59152, update the LangSmith Client SDK to version 0.8.18 or later.
What type of vulnerability is CVE-2026-59152?
CVE-2026-59152 is a path traversal vulnerability allowing arbitrary server-side file read.
Who is affected by CVE-2026-59152?
CVE-2026-59152 affects servers running the LangSmith Client SDK's TracingMiddleware prior to version 0.8.18.
What can an attacker do with CVE-2026-59152?
An attacker can send an HTTP request that lets the server read arbitrary files from its local filesystem.