Server-Side Request Forgery Vulnerability in LangSmith Client SDKs
CVE-2026-25528

5.8MEDIUM

Key Information:

Vendor

Langchain-ai

Status
Langsmith-sdk
Vendor
CVE Published:
9 February 2026

What is CVE-2026-25528?

The LangSmith Client SDKs expose a critical vulnerability that allows attackers to exploit the distributed tracing feature through Server-Side Request Forgery. By injecting malicious api_url values into the baggage header, an attacker can manipulate the SDK to exfiltrate sensitive trace data to controlled endpoints. This occurs when the SDK's post() and patch() methods are called, sending sensitive information to URLs without proper validation. The vulnerability is resolved in the latest versions of both the Python and JavaScript SDKs, underscoring the importance of timely updates for security.

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Deploy the Patch

Affected Version(s)

langsmith-sdk >= 0.4.10, <0.6.3

References

https://github.com/langchain-ai/langsmith-sdk/security/ad...
x_refsource_CONFIRM

CVSS V3.1

Score:
5.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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