Pydantic AI: Excessive resource use when local web fetching converts nested HTML

SummaryApplications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. DetailsNested block elements cause HTML-to-Markdown conversion t...

PYSEC-2026-4281 Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Summary Applications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. Details Nested block elements cause HTML-to-Markdown conversion...

Pydantic AI: Excessive resource use when local web fetching converts nested HTML

SummaryApplications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. DetailsNested block elements cause HTML-to-Markdown conversion t...

CVE-2026-107288

A flaw was found in pydantic-ai. The web fetching utilities fail to normalize domain names before checking them against the configured blocklist. A remote attacker capable of influencing the model output can supply alternate character encodings, case variations, or trailing labels that resolve to...

CVE-2026-107290

A flaw was found in pydantic-ai. An inefficient content parsing mechanism in the web fetching component allows a remote attacker serving a crafted web page to trigger a Denial of Service DoS. By providing specially structured or deeply nested content, the attacker can block the application's even...

CVE-2026-107287

A flaw was found in pydantic-ai. When local web fetching processes attacker-controlled web content, converting HTML containing deeply nested block elements into Markdown causes excessive CPU and memory consumption. A remote attacker can exploit this vulnerability to trigger a Denial of Service Do...

GHSA-V36G-JCW9-X7CW Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Summary Applications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. Details Nested block elements cause HTML-to-Markdown conversion...

Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Summary Applications using Pydantic AI's local web-fetch tool can experience excessive CPU and memory use when it converts attacker-controlled HTML. An agent must fetch the affected page; provider-native web fetching is not affected. Details Nested block elements cause HTML-to-Markdown conversion...

CVE-2026-107287 Pydantic AI: Excessive resource use when local web fetching converts nested HTML

Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.7 and 2.52.0, the local webfetchtool and the WebFetch local fallback can consume excessive CPU and memory during HTML-to-Markdown conversion of attacker-controlled HTML...

The Innocent Courier: Covert Exfiltration through Legitimate LLM Web Fetching

With the increasing capabilities of Large-Language-Models LLMs and LLM-based agents, users are increasingly using them to solve everyday problems, such as answering e-mails or providing programming support. Existing work has extensively investigated security and privacy risks, such as prompt...