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Medium, CVSS 6.8amended

Pydantic AI: Unvalidated UploadedFile references in UI adapters allow server-side file access using the application's credentials

CVE-2026-54249GHSA-h7p7-w5gc-xj3w

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (pydantic-ai 2.0.0b6, 1.106.0; pydantic-ai-slim 2.0.0b6, 1.106.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI pydantic-ai

    Affected
    >= 1.65.0, < 1.106.0>= 2.0.0b1, < 2.0.0b6
    Fixed in
    1.106.0, 2.0.0b6

  • PyPI pydantic-ai-slim

    Affected
    >= 1.65.0, < 1.106.0>= 2.0.0b1, < 2.0.0b6
    Fixed in
    1.106.0, 2.0.0b6

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.8 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
EPSS
  • CVE-2026-54249: 0.32% estimated exploitation activity in the next 30 days; percentile 24.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A client that can submit message history to a Pydantic AI UI adapter can reference arbitrary files in the application's model-provider or cloud-storage account. The server forwards the reference to the model provider, which fetches it using the server's own credentials, allowing the client to read files it should not have access to. Details UI adapters reconstruct file parts from client-submitted message history and forward them to the model provider. File URL parts are validated against a scheme allowlist before being forwarded, but 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, a client that crafts message history containing an attacker-chosen UploadedFile can cause the server to read objects belonging to its own account or…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-h7p7-w5gc-xj3w

  2. Revision 1 · created ·

    Published from ghsa record GHSA-h7p7-w5gc-xj3w

Agent brief

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# Patch Next advisory brief: CVE-2026-54249

Advisory: Pydantic AI: Unvalidated UploadedFile references in UI adapters allow server-side file access using the application's credentials
IDs: CVE-2026-54249, GHSA-h7p7-w5gc-xj3w
Record: https://patchnext.com/advisories/cve-2026-54249 (revision 2, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pydantic-ai 2.0.0b6, 1.106.0; pydantic-ai-slim 2.0.0b6, 1.106.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pydantic-ai: affected >= 1.65.0, < 1.106.0; >= 2.0.0b1, < 2.0.0b6; fixed in 1.106.0, 2.0.0b6
- PyPI pydantic-ai-slim: affected >= 1.65.0, < 1.106.0; >= 2.0.0b1, < 2.0.0b6; fixed in 1.106.0, 2.0.0b6

## Suggested inspection (read-only)
- `python -m pip show pydantic-ai`: prints the installed version. Run with the environment that serves production active.
- `python -m pip show pydantic-ai-slim`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pydantic-ai, pydantic-ai-slim.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-h7p7-w5gc-xj3w (GitHub-reviewed advisory GHSA-h7p7-w5gc-xj3w lists affected ranges: PyPI pydantic-ai-slim >=1.65.0 =2.0.0b1 =1.65.0 =2.0.0b1 <2.0.0b6)

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