# CVE-2026-57565: Readest: Cross-tenant object write via unsanitized fileName in /api/storage/upload (object-key path traversal)

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 apps/readest-app/src/pages/api/storage/upload.ts route constructed an object key from the authenticated user's identifier and a client-controlled fileName without rejecting path separators or parent-directory traversal. In the R2 backend, apps/readest-app/src/utils/r2.ts placed that key into a new Request URL before signing it, and URL normalization collapsed parent-directory components so the resulting presigned PUT could escape the caller's namespace. An authenticated attacker who knew a target user identifier and book hash could overwrite or poison that user's stored book object and corrupt the associated file_key metadata; the exact cross-tenant escape was verified for the R2 backend. 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: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-22

## Exploit evidence

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

## References

- https://github.com/readest/readest/security/advisories/GHSA-mfmj-2frf-vhgw (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-2026-57565; retrieved 2026-11-04; source updated 2026-11-04

Revision: c00d23c4d868e4d2b564dd928c0d5c772e304fd290e6e5b8ae03bc76327fb85a

Canonical: https://y2.dev/cve/CVE-2026-57565

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