CVE-2026-57566

Received Received - Intake

Server-Side Request Forgery in Readest Ebook Reader

Publication date: 2026-11-04

Last updated on: 2026-11-04

Assigner: GitHub, Inc.

Description

Readest is a modern, feature-rich ebook reader designed for seamless cross-platform access and an intuitive reading experience. Prior to 0.11.10, the unauthenticated /api/opds/proxy route in apps/readest-app/src/app/api/opds/proxy/route.ts accepted an attacker-controlled URL and fetched it server-side without restricting the scheme, blocking private, loopback, link-local, or metadata hosts, or revalidating destinations during automatic redirect following. The route also accepted caller-controlled outbound headers and Authorization values and reflected the upstream status and response body. A remote attacker could use the service as an open request proxy and, on Node, Docker, or other self-hosted deployments with internal-network access, retrieve cloud metadata or internal-service responses. Cloudflare Workers deployments restrict access to link-local and private destinations, which reduces the internal-network impact there, but the unauthenticated public fetch-and-reflect behavior remains. This issue is fixed in version 0.11.10.

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Meta Information

Published

2026-11-04

Last Modified

2026-11-04

Generated

2026-11-05

AI Q&A

2026-11-05

EPSS Evaluated

N/A

NVD

CVE-2026-57566

Affected Vendors & Products

Vendor	Product	Version / Range
readest	readest	< 0.11.10

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-918	The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

Executive Summary

This vulnerability is in Readest, an ebook reader app. Before version 0.11.10, an unauthenticated API endpoint /api/opds/proxy could fetch arbitrary URLs server-side without proper restrictions. Attackers could exploit this to retrieve internal service responses or cloud metadata if the app was deployed on a network with internal access.

Detection Guidance

Check if your Readest instance is running a version prior to 0.11.10. Inspect network traffic for requests to /api/opds/proxy with external or internal URLs. Look for unusual outbound requests or responses reflecting internal service data.

Impact Analysis

If you use Readest before version 0.11.10, an attacker could use your server as a proxy to fetch sensitive internal data or cloud metadata. This could expose internal services, API keys, or other confidential information if your deployment has internal network access.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Unauthorized data exposure risks non-compliance with these regulations.

Mitigation Strategies

Upgrade Readest to version 0.11.10 or later immediately. If upgrading is not possible, restrict access to the /api/opds/proxy endpoint or disable it entirely. Review network configurations to block unauthorized outbound requests.

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