Quick answers
- Is CVE-2026-57566 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-57566 being exploited in the wild.
- How severe is CVE-2026-57566?
- Critical severity, with a CVSS score of 9.3, published 4 November 2026.
- Which products and versions are affected?
- Readest before 0.11.10.
- Is there a fix for CVE-2026-57566?
- Yes: fixed in 0.11.10. Until then: Upgrade to version 0.11.10 or later. Cloudflare Workers deployments automatically restrict access to link-local and private addresses, reducing the internal-network impact. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-57566 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-57566?
- Check whether you run Readest at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 0.11.10
Upgrade to version 0.11.10 or later. Cloudflare Workers deployments automatically restrict access to link-local and private addresses, reducing the internal-network impact.
Technical details
The /api/opds/proxy endpoint in Readest prior to 0.11.10 accepted attacker-controlled URLs and fetched them server-side without validating the scheme, blocking private/loopback/link-local addresses, or re-validating redirect destinations. The endpoint also accepted caller-controlled outbound headers and reflected the upstream response. An unauthenticated remote attacker could abuse this as an open request proxy to reach internal services or cloud metadata endpoints, particularly on Node.js or Docker self-hosted deployments.
Affected products
- Readest Readest before 0.11.10
Timeline
- 2026-11-04: disclosed
- 2026-06-18: patched