# CVE-2026-57566: Readest: Unauthenticated SSRF / open request proxy in /api/opds/proxy

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- readest / readest: < 0.11.10 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 9.3 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-918

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/readest/readest/security/advisories/GHSA-c7mm-g2j2-98cx (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/readest/readest/pull/4638 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/readest/readest/commit/495783d04516d05b2eb10f8f8bad297d436b36de (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/readest/readest/releases/tag/v0.11.10 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-57566; retrieved 2026-11-04; source updated 2026-11-04

Revision: afc32180cfa656eb9efcfb717494610c4f0918e1bc205d7f47d5770b7512b71d

Canonical: https://y2.dev/cve/CVE-2026-57566

## Agent and API access

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- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.