Server-side Request Forgery (SSRF) Affecting langsmith package, versions >=0.3.41 <0.4.6
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-JS-LANGSMITH-15253025
- published10 Feb 2026
- disclosed9 Feb 2026
- creditUnknown
Introduced: 9 Feb 2026
CVE-2026-25528 (opens in a new tab)How to fix?
Upgrade langsmith to version 0.4.6 or higher.
Overview
langsmith is a Client library to connect to the LangSmith Observability and Evaluation Platform.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to the improper validation of api_url and api_key fields in baggage headers in RunTree.from_headers() and RunTree.fromHeaders() functions. An attacker can cause the exfiltration of sensitive trace data to attacker-controlled endpoints by injecting arbitrary api_url values through the baggage header, which are then used by the SDK to send run data to malicious URLs.
Note:
This issue affects applications, utilising TracingMiddleware and calling RunTree.from_headers() or RunTree.fromHeaders() with untrusted HTTP headers.
Workaround
For users that are unable to upgrade to the fixed version it is recommended:
- To strip or validate the baggage header before passing to
RunTree.from_headers()orRunTree.fromHeaders(); - To not use TracingMiddleware with untrusted traffic.