LangSmith SDK TracingMiddleware: Arbitrary server-side file read

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.7 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

EPSS

• CVE-2026-59152: 0.20% estimated exploitation activity in the next 30 days; percentile 9.71 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

19 Jun 2026, 22:10 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-f4xh-w4cj-qxq8

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-f4xh-w4cj-qxq8

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# Patch Next advisory brief: CVE-2026-59152

Advisory: LangSmith SDK TracingMiddleware: Arbitrary server-side file read
IDs: CVE-2026-59152, GHSA-f4xh-w4cj-qxq8
Record: https://patchnext.com/advisories/cve-2026-59152 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: langsmith 0.8.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI langsmith: affected < 0.8.18; fixed in 0.8.18

## Suggested inspection (read-only)
- `python -m pip show langsmith`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on langsmith.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-f4xh-w4cj-qxq8 (OSV record GHSA-f4xh-w4cj-qxq8 lists affected ranges: PyPI langsmith >=0 <0.8.18 (fixed))
- Verified: https://github.com/advisories/GHSA-f4xh-w4cj-qxq8 (GitHub-reviewed advisory GHSA-f4xh-w4cj-qxq8 lists affected ranges: PyPI langsmith >=0 <0.8.18)

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