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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-45134

HIGH · 7.1 CVSS v3.1 Published 2026-05-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
LangSmith Client SDKs provide SDK's for interacting with the LangSmith platform. Prior to LangSmith SDK Python 0.8.0 and JS/TS 0.6.0, the LangSmith SDK's prompt pull methods (pull_prompt / pull_prompt_commit in Python, pullPrompt / pullPromptCommit in JS/TS) fetch and deserialize prompt manifests from the LangSmith Hub. These manifests may contain serialized LangChain objects and model configuration that affect runtime behavior. When pulling a public prompt by owner/name identifier, the manifest content is controlled by an external party, but prior versions of the SDK did not distinguish this from pulling a prompt within the caller's own organization. This vulnerability is fixed in LangSmith SDK Python 0.8.0 and JS/TS 0.6.0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The LangSmith SDK's prompt pull methods deserialize LangChain objects from manifests fetched from the LangSmith Hub. Prior to v0.8.0 (Python) and v0.6.0 (JS/TS), pulling a public prompt by owner/name allowed external parties to supply malicious serialized objects that execute upon deserialization, compromising the runtime environment.

MitigationUpgrade LangSmith SDK to Python 0.8.0+ or JS/TS 0.6.0+ to receive the fix that properly distinguishes public prompts from organizational prompts. Audit existing code that pulls public prompts for signs of compromise.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Python LangSmith SDK version
    Run `pip show langsmith` or `python -c "import langsmith; print(langsmith.__version__)"`
    Affected if Version is lower than 0.8.0 and code uses prompt pull methods
  2. Check JavaScript/TypeScript LangSmith SDK version
    Run `npm list langsmith` or check the version in package.json
    Affected if Version is lower than 0.6.0 and code uses prompt pull methods
  3. Identify prompt pull usage in Python code
    Search codebase for `client.pull(` or `langsmith.pull(` calls that fetch prompts from LangSmith Hub by owner/name
    Affected if Code pulls public prompts using owner/name identifiers from LangSmith Hub
  4. Identify prompt pull usage in JS/TS code
    Search codebase for `client.pull(` or `hub.pull(` calls that fetch prompts from LangSmith Hub by owner/name
    Affected if Code pulls public prompts using owner/name identifiers from LangSmith Hub

You are affected if your LangSmith SDK version is below 0.8.0 (Python) or 0.6.0 (JS/TS) AND your code uses prompt pull methods to fetch public prompts from the LangSmith Hub by owner/name.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade LangSmith SDK to Python 0.8.0+ or JS/TS 0.6.0+ to receive the fix that properly distinguishes public prompts from organizational prompts. Audit existing code that pulls public prompts for signs of compromise.

Recommended fix High confidence

LangSmith SDK Python 0.8.0+ and JS/TS 0.6.0+

  1. Identify which LangSmith SDK is in use (Python or JavaScript/TypeScript)
  2. For Python: Check current version with `pip show langsmith` or in requirements.txt
  3. For JS/TS: Check current version with `npm list langsmith` or `yarn list langsmith`
  4. For Python: Upgrade to version 0.8.0 or later using `pip install langsmith>=0.8.0`
  5. For JS/TS: Upgrade to version 0.6.0 or later using `npm install langsmith@^0.6.0` or `yarn add langsmith@^0.6.0`
  6. Verify the upgrade was successful by checking the installed version
  7. Review the SDK release notes for the new version to ensure compatibility with your application
Caveat Check the LangSmith SDK changelog for any breaking changes between your current version and 0.8.0 (Python) / 0.6.0 (JS/TS)

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,210
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45134 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data