Answer in brief
CVE-2026-107288 records a Low severity (CVSS 3.7) vulnerability in Pydantic AI: web_fetch_tool blocked_domains bypass via a hostname the resolver normalizes differently. The current sources do not mark it as known exploited. The current feed maps pydantic/pydantic-ai (generic), pydantic/pydantic-ai-slim (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 3.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps pydantic/pydantic-ai (generic), pydantic/pydantic-ai-slim (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| pydantic/pydantic-aigeneric | >=1.77.0 <1.107.6 || >=2.0.0b1 <2.44.0 | 1.107.6, 2.44.0 |
| pydantic/pydantic-ai-slimgeneric | >=1.77.0 <1.107.6 || >=2.0.0b1 <2.44.0 | 1.107.6, 2.44.0 |
Published upstream
Oct 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 8, 2026
Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.6 and 2.44.0, the local web_fetch_tool and the WebFetch local fallback compare blocked_domains entries with a URL hostname before both values are normalized to the form used by getaddrinfo. An attacker-influenced model can use an equivalent IDNA spelling, non-ASCII label separator, case variation, or trailing root label that resolves to a blocked host but does not match the configured string, causing the application to fetch that host with its own privileges. allowed_domains fails closed for unmatched spellings, and private-IP and cloud-metadata protections remain effective. This issue is fixed in versions 1.107.6 and 2.44.0.
Quoted source text, attributed separately from HOL analysis.