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TI-2026-85221 Aliases CVE-2026-57566

Server-side request forgery in Readest OPDS proxy

Priority HIGH 79CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Readest before 0.11.10 has a server-side request forgery flaw (CWE-918) in its unauthenticated /api/opds/proxy route. It fetches a caller-supplied URL server-side without restricting the scheme or blocking private or metadata hosts. A remote attacker can use it as an open proxy to reach cloud metadata or internal services on Node, Docker, or self-hosted deployments. Cloudflare Workers blocks link-local and private destinations, but public fetch-and-reflect remains.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00581 48th percentileScored 2026-11-07
Fix Fixed readest (readest): 0.11.10

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
readestreadestbefore 0.11.100.11.10Patch availableCNA
  • readest Vendorreadest Affected before 0.11.10 Fixed in 0.11.10 Patch available CNA

Remediation

Upgrade Readest to version 0.11.10, the fixed version. Versions before 0.11.10 are affected.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA readest (readest) Fixed in 0.11.10

Timeline

  1. 2026-11-04 Threatist record created from CVE-2026-57566
  2. 2026-11-05 CISA SSVC decision points changed
  3. 2026-11-05 Priority changed: MEDIUM → HIGH

References

  • TI-2026-85222 Path traversal in Readest Tauri commands allows arbitrary file access CVSS 3.1HIGH 8.6
  • TI-2026-85220 Path traversal in Readest upload overwrites other users' books CVSS 3.1MEDIUM 6.5
  • TI-2026-85219 Authorization bypass in Readest lets users hijack paid subscriptions CVSS 3.1MEDIUM 6.5
  • TI-2026-56980 Readest: unsanitized iframe srcdoc attribute in the EPUB sanitizer can lead to arbitrary code execution CVSS 3.1HIGH 8.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences