AI Security Breach

## Description 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. Prompt manifests can intentionally configure a model with a custom base URL, default headers, model name, or other constructor arguments. These are supported features, but they also mean the prompt contents should be treated as executable configuration rather than plain text. A prompt can also include serialized LangChain `Runnable` or `PromptTemplate` objects with attacker-controlled constructor kwargs, or secret references that, if `secrets_from_env` is enabled, read environment variables at deserialization time. Applications are exposed when all of the following are true: - The application calls `pull_prompt` or `pull_prompt_commit` (Python) or `pullPrompt` or `pullPromptCommit` (JS/TS) with a public `owner/name` prompt identifier. - The prompt was published or modified by an untrusted or compromised account. - The application uses the pulled prompt without independently validating its contents. Applications that only pull prompts from their own organization (referenced by name only, without an `owner/` prefix) are not affected by the public prompt trust boundary issue described above. However, same-organization prompts carry their own risk. If an attacker gains write access to the organization (for example, through a leaked `LANGSMITH_API_KEY` or a compromised team member account), they can push a malicious prompt that is pulled and deserialized without any additional warning. ## Impact An attacker who publishes a m

What Happened

## Description 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. Prompt manifests can intentionally configure a model with a custom base URL, default headers, model name, or other constructor arguments. These are supported features, but they also mean the prompt contents should be treated as executable configuration rather than plain text. A prompt can also include serialized LangChain `Runnable` or `PromptTemplate` objects with attacker-controlled constructor kwargs, or secret references that, if `secrets_from_env` is enabled, read environment variables at deserialization time. Applications are exposed when all of the following are true: - The application calls `pull_prompt` or `pull_prompt_commit` (Python) or `pullPrompt` or `pullPromptCommit` (JS/TS) with a public `owner/name` prompt identifier. - The prompt was published or modified by an untrusted or compromised account. - The application uses the pulled prompt without independently validating its contents. Applications that only pull prompts from their own organization (referenced by name only, without an `owner/` prefix) are not affected by the public prompt trust boundary issue described above. However, same-organization prompts carry their own risk. If an attacker gains write access to the organization (for example, through a leaked `LANGSMITH_API_KEY` or a compromised team member account), they can push a malicious prompt that is pulled and deserialized without any additional warning. ## Impact An attacker who publishes a m

Why This Matters

Current evidence identifies a security issue involving LangSmith SDK, but does not yet support a more specific impact claim.

Recommended Action

No confirmed vendor remediation is available in the current evidence. Confirm whether LangSmith SDK is present in your environment and review the affected configuration.

Exposure

Exposure reason: This incident does not currently match a technology in My Interests.

Exploitation status: UNKNOWN

Primary entities:

Timeline

• Incident first seen
  May 13, 2026 20:59

  BugSkan first recorded this incident.

• LangSmith SDK: Public prompt pull deserializes untrusted manifests without trust boundary warning
  May 13, 2026 20:59

  OSV.dev · Research

Sources

My Interests Match