CVE
Synology DiskStation Manager arbitrary file read and write in Auth API
- Exploited
- No known exploitation
- Fix
- Fixed in 7.4.1-90080-1, 7.3.2-86009-5
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affected: Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1 (Auth API).
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.89% · 59th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
A missing critical authentication step in the Auth API of Synology DiskStation Manager (DSM) lets a remote attacker with a valid login read or write arbitrary files and cause denial of service. The attack can be carried out over the network.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
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.
Who should check
Teams running Synology DiskStation Manager (DSM) 7.3 or 7.4 NAS devices with the Auth API exposed to remote authenticated users.
Read the source excerpt
“Auth API in Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.8/10CVSS 8.8
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Affected: Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1 (Auth API).Upgrade to a fixed version: 7.4.1-90080-1, 7.3.2-86009-5.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-74857 (A missing critical step in authentication vulnerability in the Auth API in Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and…), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-74857 (entry last updated 2026-11-12):
Affected:
- Synology DiskStation Manager (DSM): from 7.4.1, fixed in 7.4.1-90080-1; from 7.3.2, fixed in 7.3.2-86009-5
Fixed versions: 7.4.1-90080-1, 7.3.2-86009-5.
Conditions (all must be true for the bug to be hit):
- Affected: Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1 (Auth API). (source: https://www.synology.com/en-global/security/advisory/Synology_SA_26_18)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, low-privilege login, no user action.
CISA KEV: CVE-2026-74857 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-74857 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://www.synology.com/en-global/security/advisory/Synology_SA_26_18
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-74857
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-74857"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- Synology DiskStation Manager (DSM)
From 7.4.1 · fixed in 7.4.1-90080-1; From 7.3.2 · fixed in 7.3.2-86009-5
Evidence 3
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Link
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-74857
Is CVE-2026-74857 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The Auth API in Synology DiskStation Manager has a missing critical authentication step. Authenticated remote users can use it to read or write arbitrary files and to cause denial of service.Source: synology.com
Which versions are affected by CVE-2026-74857?
DiskStation Manager (DSM): from 7.4.1 before 7.4.1-90080-1; from 7.3.2 before 7.3.2-86009-5.Source: cve.now feed data
Am I affected, and how do I check?
Affected versions are DSM before 7.3.2-86009-5 on the 7.3.2 line and before 7.4.1-90080-1 on the 7.4.1 line, with the Auth API in use. Check your DSM version in the control panel or with the DSM version information shown on the system info page.Source: synology.com
How do I fix CVE-2026-74857?
The facts give no fixed build beyond the listed versions, so update DSM to 7.3.2-86009-5 or later on the 7.3.2 line, or to 7.4.1-90080-1 or later on the 7.4.1 line.Source: synology.com