Pydantic AI Updates: October 21, 2026

1. Pydantic AI 2.59.0 and 1.107.9 Fix a High-Severity web_fetch Advisory

Pydantic AI. Pydantic AI released v2.59.0 and v1.107.9 on October 20 to fix GHSA-4whf-38hw-pxxh, rated high severity. When web_fetch_tool fetched attacker-controlled HTML containing many elements, the HTML conversion step could delay unrelated work running in the same process. The maintainers advise upgrading if the tool can fetch such pages. Source

2. v2.59.0 Adds a Daytona Sandbox, Eleven Realtime Support, and Provider-Neutral Model Errors

Pydantic AI. The release adds DaytonaSandbox, a workspace that runs Coder, Shell, FileSystem, and other harness capabilities inside a Daytona sandbox, and ElevenLabsRealtimeModel for ElevenLabs’ new Eleven Realtime speech-to-speech models. New provider-neutral error categories such as ModelRateLimitError, ModelUnavailableError, and ModelContextWindowExceededError arrive alongside a non_retryable_model_errors option that stops Temporal from retrying specific categories. Compatibility notes include removal of shut-down Groq models and a new UsageLimitUnavailableWarning that distinguishes omitted provider usage from reported zero usage. Source