---
id: "CVE-2026-121544"
kind: "vulnerability"
aliases: ["CVE-2026-121544"]
title: "Koodo Reader: OPDS cover handler lets authenticated users read server files"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["koodo-reader", "package", "self-hosted"]
not_affected_if: ["auth-required", "default-config"]
published_at: "2026-11-03T16:17:25+00:00"
first_seen_at: "2026-11-03T16:21:43+00:00"
updated_at: "2026-11-03T16:23:59+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121544", "first_seen_at": "2026-11-03T16:21:43+00:00"}]
---

# Koodo Reader: OPDS cover handler lets authenticated users read server files

Koodo Reader through 2.4.6 has a path traversal flaw in the OPDS handlers of its self-hosted HTTP server. An authenticated attacker can upload a crafted books.db with ../ sequences in a cover value and then read files the server process can access.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether the Koodo Reader self-hosted HTTP server is running, which the sources imply is the affected mode.
- Check the installed Koodo Reader version against the range in the sources (through `2.4.6`).

## Fix

- Koodo Reader: unknown; the sources link a patch on github.com but do not state the fixed version here.

## Timeline

- 2026-11-03T16:21:43+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121544

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/koodo-reader-through-2.4.6-path-traversal-via-opds-cover-and-download-handlers
- [fix] Patch: github.com https://github.com/koodo-reader/koodo-reader/commit/cbc79a1ab5cbbd61c8252d6ab3cc6dbb694663b8

## From the sources

Koodo Reader through 2.4.6 contains a path traversal vulnerability in the self-hosted HTTP server's OPDS handlers that allows authenticated attackers to read files outside the upload directory. Attackers can upload a crafted books.db with a cover value containing ../ sequences, then request /opds/cover/{key} to read files accessible to the server process.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_