CVE-2026-41182CWE-200CWE-359CWE-532

LangSmith SDK: Streaming token events bypass output redaction

Medium · published April 23, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
28.3
In the wild
Unconfirmed
What it is

LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to version 0.5.19 of the JavaScript SDK and version 0.7.31 of the Python SDK, 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. Version 0.5.19 of the JavaScript SDK and version 0.7.31 of the Python SDK fix the issue.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00358 · 28.3th percentile
Weaknesses
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor; CWE-359 · Exposure of Private Personal Information to an Unauthorized Actor; CWE-532 · Insertion of Sensitive Information into Log File
Published
2026-04-23T00:14Z
EPSS history
Timeline
  • 23 APR 00:14Z
    LangSmith SDK: Streaming token events bypass output redaction
    cvelistv5