CVE-2026-41182 — langsmith
MEDIUMCVE-2026-41182 is a medium-severity (CVSS 5.3) Information Exposure vulnerability in langsmith. A fix is available for langsmith — see the affected versions and patch details below.
LangSmith SDK: Streaming token events bypass output redaction
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41182.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
langsmithnpmDescription
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:997-1003andtraceable.ts:1044-1050 - Python SDK:
run_helpers.py:1924andrun_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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | langsmith | all versions | 0.5.19npm install langsmith@0.5.19 |
| 🐍PyPI | langsmith | all versions | 0.7.31pip install --upgrade 'langsmith==0.7.31' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for langsmith, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update langsmith to 0.5.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41182 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is CVE-2026-41182 in your dependencies?
Find it across npm, PyPI, including transitive dependencies.