---
id: "CVE-2026-74857"
page: "https://infrastack.ai/live/CVE-2026-74857"
kind: "vulnerability"
aliases: ["CVE-2026-74857"]
title: "Synology DSM: Auth API flaw lets logged-in users read or write files"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["dsm", "infrastructure", "nas", "self-hosted", "synology"]
not_affected_if: ["no-remote-access", "patched-dsm-version"]
published_at: "2026-11-12T04:17:20+00:00"
first_seen_at: "2026-11-12T04:47:09+00:00"
updated_at: "2026-11-12T04:47:36+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74857", "first_seen_at": "2026-11-12T04:47:09+00:00"}]
exploit_sources: []
---

# Synology DSM: Auth API flaw lets logged-in users read or write files

Link for people: https://infrastack.ai/live/CVE-2026-74857 (this .md is for agents)

Synology DiskStation Manager has a missing authentication step in its Auth API, so a remote user who already has an account can read or write arbitrary files on the NAS. The same flaw can also be used to knock the device offline with denial-of-service attacks.

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

## How to check

- Check the DSM version under Control Panel > Info Center; compare it with the fixed versions listed below.
- Confirm whether remote access to DSM is exposed to the internet, for example through QuickConnect or a port forward.

## Fix

- DSM `7.3.2-86009-5` or later for the 7.3 branch
- DSM `7.4.1-90080-1` or later for the 7.4 branch

## Timeline

- 2026-11-12T04:47:09+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-74857

## From the sources

A missing critical step in authentication vulnerability in the Auth API in Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1 allows remote authenticated users to read or write arbitrary files and conduct denial-of-service attacks.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_