---
id: "CVE-2026-57448"
kind: "vulnerability"
aliases: ["CVE-2026-57448"]
title: "Blombooru: admin image proxy fetches internal addresses, exposing cloud metadata"
severity: "medium"
cvss: 6.2
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["blombooru", "cloud-hosted", "other", "self-hosted"]
not_affected_if: ["no-admin-exposure", "version-1.40.0-or-later"]
published_at: "2026-10-28T22:17:15+00:00"
first_seen_at: "2026-10-28T22:35:35+00:00"
updated_at: "2026-10-28T22:36:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-57448", "first_seen_at": "2026-10-28T22:35:35+00:00"}]
---

# Blombooru: admin image proxy fetches internal addresses, exposing cloud metadata

Blombooru's administrator-only image proxy endpoint fetches any URL server-side without blocking private, loopback or link-local addresses, and follows redirects into them. An administrator can use it to probe internal services and read cloud instance metadata, potentially including IAM credentials.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Blombooru version; instances below `1.40.0` are affected.
- Look for the `/api/booru-import/proxy-image` route in `backend/app/routes/booru_import.py`.

## Fix

- Upgrade Blombooru to `1.40.0` or later.

## Timeline

- 2026-10-28T22:35:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-57448

## From the sources

Blombooru is a self-hosted personal booru for organizing and tagging private image collections. Prior to 1.40.0, the administrator-only `GET /proxy-image` endpoint, exposed as `/api/booru-import/proxy-image`, accepts a `url` query parameter and fetches it server-side without meaningful destination validation. `proxy_image()` in `backend/app/routes/booru_import.py` only checks whether the value starts with http, then uses `get_client_for_url` or `requests.get` and streams the response. Private, loopback and link-local addresses are not blocked, and automatically followed redirects can move a request from a trusted domain to an internal address. An authenticated administrator can enumerate internal services and access cloud instance metadata, potentially disclosing IAM credentials and crossing the application's intended cloud or network trust boundary. The reporter also observed a hanging recursive self-request. Administrator authentication remains a prerequisite; this is not an anonymous proxy. This issue is fixed in version 1.40.0.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_