LangSmith SDK TracingMiddleware: Arbitrary server-side file readGHSA-f4xh-w4cj-qxq8
HIGHGHSA-f4xh-w4cj-qxq8 is a high-severity (CVSS 7.7) Path Traversal vulnerability in langsmith. A fix is available for langsmith — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- 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 GHSA-f4xh-w4cj-qxq8.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-f4xh-w4cj-qxq8 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,492 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
langsmithReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
An attacker who can send an HTTP request to a server running the LangSmith SDK's TracingMiddleware can cause that server to read an arbitrary file from its local filesystem and upload the contents to LangSmith as a trace attachment. Depending on how the distributed trace system is deployed, triggering a read may not require authentication. Retrieving the contents requires read access to the LangSmith workspace the traces are sent to. The net effect is a trust-boundary crossing: a party with workspace trace-read access (for example a low-privilege workspace member, a contractor, or a compromised teammate account) gains the ability to read files from any server running TracingMiddleware, a capability outside that workspace's intended trust boundary.
Impact
Confidentiality (High): arbitrary read of files accessible to the server process, exposed to anyone with workspace trace-read access.
Details
Two defects combine. A field supplied through a tracing-propagation header was merged into the run without validation, allowing injection of run attributes including attachments (CWE-346). A type check intended to gate filesystem access did not match the type of the decoded input, so the guard never engaged (CWE-843). As a result, an attacker-named file is opened by the server and uploaded as a trace attachment by the background tracing thread (CWE-22).
Who can exploit this
- Anyone reachable by HTTP can trigger the file read. Depending on how the distributed trace system is deployed, triggering may not require authentication.
- Retrieving the file contents requires read access to the destination LangSmith workspace. The upload uses the server's own configured API key and workspace, which the attacker cannot redirect, so a zero-access outsider cannot retrieve the result; a workspace member, or anyone who has compromised one, can.
Remediation
Upgrade the Python SDK to >= 0.8.18.
Workarounds
Until upgrading, do not expose TracingMiddleware to untrusted HTTP traffic, and limit workspace trace-read access to trusted members.
Credits
First reported by @Ryu7zz.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | langsmith | all versions | 0.8.18pip install --upgrade 'langsmith==0.8.18' |
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 0.8.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f4xh-w4cj-qxq8 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is GHSA-f4xh-w4cj-qxq8 in your dependencies?
Find it across PyPI, including transitive dependencies.