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LangSmith SDK: Streaming token events bypass output redaction

Moderate severity GitHub Reviewed Published Apr 14, 2026 in langchain-ai/langsmith-sdk • Updated Apr 24, 2026

Package

npm langsmith (npm)

Affected versions

<= 0.5.18

Patched versions

0.5.19
pip langsmith (pip)
<= 0.7.30
0.7.31

Description

Summary

The LangSmith SDK's output redaction controls (hideOutputs in JS, hide_outputs in Python) do not apply to streaming token events. When an LLM run produces streaming output, each chunk is recorded as a new_token event containing the raw token value. These events bypass the redaction pipeline entirely — prepareRunCreateOrUpdateInputs (JS) and _hide_run_outputs (Python) only process the inputs and outputs fields on a run, never the events array. As a result, applications relying on output redaction to prevent sensitive LLM output from being stored in LangSmith will still leak the full streamed content via run events.

Details

Both JS and Python SDKs are affected. The same pattern exists in both:

  • JS SDK: traceable.ts:997-1003 and traceable.ts:1044-1050
  • Python SDK: run_helpers.py:1924 and run_helpers.py:1996

In both SDKs, new_token events with raw kwargs.token values are added during streaming, and the redaction pipeline (hideOutputs in JS, hide_outputs in Python) only processes inputs/outputs — never events.

References

@jkennedyvz jkennedyvz published to langchain-ai/langsmith-sdk Apr 14, 2026
Published to the GitHub Advisory Database Apr 16, 2026
Reviewed Apr 16, 2026
Published by the National Vulnerability Database Apr 23, 2026
Last updated Apr 24, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(12th percentile)

Weaknesses

Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Learn more on MITRE.

Exposure of Private Personal Information to an Unauthorized Actor

The product does not properly prevent a person's private, personal information from being accessed by actors who either (1) are not explicitly authorized to access the information or (2) do not have the implicit consent of the person about whom the information is collected. Learn more on MITRE.

Insertion of Sensitive Information into Log File

The product writes sensitive information to a log file. Learn more on MITRE.

CVE ID

CVE-2026-41182

GHSA ID

GHSA-rr7j-v2q5-chgv

Source code

Credits

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