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CVE-2026-57566

CRITICALCVSS 9.3/10EPSS 0.58%

Last modified

CVE-2026-57566 is a critical-severity vulnerability rated 9.3/10 on the CVSS scale. 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. EPSS estimates a 0.58% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
9.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

EPSS Probability
0.58%

47.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
readestreadest< 0.11.10

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-57566?
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.
How severe is CVE-2026-57566?
CVE-2026-57566 has a CVSS score of 9.3/10 (CRITICAL severity). The EPSS model estimates a 0.58% probability of exploitation in the next 30 days.
How do I fix CVE-2026-57566?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST