Critical LangSmith Account Takeover Vulnerability Puts Users at Risk

Miggo Security disclosed a critical LangSmith vulnerability (CVE-2026-25750) in the Studio front-end: an attacker-controlled baseUrl could be used to route an authenticated user's API requests and session tokens to a malicious domain, allowing silent account takeover and potential access to raw AI traces, system prompts, and sensitive data. LangChain mitigated the issue by implementing a strict allowed-origins policy; cloud customers were remediated by December 15, 2025, and self-hosted administrators must upgrade to LangSmith 0.12.71 or Helm chart langsmith-0.12.33+ to be protected. The advisory states there is no evidence of active exploitation in the wild.