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QNAP Download Station EUVDEUVD-2026-101977

| CVE-2026-39989 MEDIUM
Server-Side Request Forgery (SSRF) (CWE-918)
2026-10-15 qnap GHSA-gxh4-v8pp-4j5f
5.3
CVSS 4.0 · Vendor: qnap
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain valid Download Station user account
  2. Exploit
    Submit crafted URL/download request
  3. Execution
    Server performs attacker-directed fetch
  4. Impact
    Read internal application data

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V4 - API and Web Service URL allowlisting, SSRF prevention
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Credential Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires a valid Download Station user account on the target QNAP system (PR:L) - the description explicitly states the attacker must first 'gain a user account,' making this unexploitable by fully unauthenticated attackers. Exploitation is remote over the network (AV:N) with low complexity (AC:L) and no user interaction (UI:N), but is limited to confidentiality disclosure of application data (VC:L) with no write or denial-of-service impact. The primary limiting factor is the authentication requirement; the specific Download Station feature or URL-fetch function that triggers the SSRF is not detailed in the available data. Affected deployments are QNAP systems running Download Station versions earlier than 5.10.1.312 (and the 5.11 branch earlier than 5.11.2.321).

Impact

This is a moderate-severity, authentication-gated issue rather than an urgent priority. The vendor-supplied CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N) scores 5.3 and the signals are internally consistent: network-reachable (AV:N), low complexity (AC:L), but requiring low-level privileges (PR:L), which matches the description's explicit precondition that the attacker 'gains a user account.' Impact is limited to confidentiality (VC:L) with no integrity or availability effect, consistent with a read-only SSRF used to 'read application data.' No EPSS score, no CISA KEV listing, and no public POC are present in the provided data, so there is no evidence of active or probable near-term exploitation - exploitation status is 'no public exploit identified at time of analysis.' The dominant limiting factor is the authentication requirement (PR:L): a valid Download Station user account is a real barrier that pushes this toward an insider or post-credential-compromise scenario rather than mass opportunistic exploitation. Missing signals (EPSS, POC status) are unknowns, not contradictions; no conflicting data was observed between the CVSS vector and the description.

Exploit ScenarioDerived

An attacker who has obtained a valid Download Station user account (via phishing, credential reuse, or a weak/low-privilege account) submits a crafted request that causes the server to fetch an attacker-controlled or internal URL. The server-side request returns internal application data to the attacker, enabling reconnaissance of otherwise non-exposed resources. No public exploit code is identified at time of analysis, and the network attack vector with low complexity means exploitation is straightforward once authenticated.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 15, 2026

Server-side request forgery in QNAP Download Station allows a low-privileged authenticated user to make the NAS application issue requests to internal or arbitrary destinations, resulting in limited disclosure of application data rather than any modification or denial of service. The flaw affects Download Station builds before 5.10.1.312 and the 5.11.x line before 5.11.2.321, and QNAP has published fixed versions for each branch. The issue is authentication-gated (CVSS 4.0 base 5.3, PR:L, confidentiality-only; independent assessment restricts impact to VC:L/VI:N/VA:N), and no public exploit code or confirmed active exploitation (CISA KEV) was identified at time of analysis.

RemediationAI

Upgrade Download Station to 5.10.1.312 (5.10 branch) or 5.11.2.321 (5.11 branch) or later through the QNAP App Center, using the vendor release notes at https://www.qnap.com/en/app_releasenotes/list.php?app_choose=DownloadStation to confirm the installed version and update path; these are vendor-released patches that fully address the reported SSRF. If immediate updating is not possible, reduce the PR:L prerequisite by disabling or deleting unused Download Station accounts and restricting the application to trusted, minimally privileged users - this does not fix the flaw and only shrinks the attacker pool. As a compensating control, constrain the NAS's outbound and internal reachability with QNAP Network Access Protection or firewall rules that block Download Station traffic to localhost, management ports, and link-local/metadata ranges; the trade-off is that legitimate download, RSS, and LAN-integration features may stop working and rules must be reviewed so normal download traffic is not broken. Logging and monitoring Download Station activity for anomalous outbound URL fetch attempts can provide early warning, but neither workaround replaces installing the fixed builds.

Affected VersionsENISA

Download Station 5.10.x <5.10.1.312
Download Station 5.11.x <5.11.2.321

Affected Packages

euvd download_station fix: 5.10.1.312, 5.11.2.321

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This is a classic server-side request forgery (CWE-918) in QNAP's Download Station, the download-manager application that runs on QNAP QTS/QuTS hero NAS systems and supports adding tasks from user-supplied URLs (including HTTP/FTP links and RSS feed subscriptions). When the application fetches a URL supplied by a user, it fails to adequately validate or restrict the destination, so the NAS's own network position and credentials can be leveraged to reach internal-only endpoints, localhost services, or cloud metadata-style addresses and return the retrieved content back to the requester. The reported CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N) confirms network-reachable, low-complexity, no-user-interaction exploitation that requires a valid low-privileged Download Station account and yields only limited confidentiality impact - no integrity or availability effects. The affected CPE, cpe:2.3:a:qnap_systems_inc.:download_station:*:*:*:*:*:*:*:*, identifies all Download Station releases as the affected product, with the specific fixes split across the 5.10 and 5.11 release branches.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (qnap) PRIMARY 5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.3 MEDIUM

Network-reachable SSRF requiring a low-privilege authenticated account (PR:L), low-complexity, read-only data disclosure so C:L with I:N/A:N and unchanged scope.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (qnap).

CVSS VectorVendor: qnap

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
Patch available
Oct 15, 2026 - 11:02 EUVD

DescriptionCVE.org

A server-side request forgery (SSRF) vulnerability has been reported to affect Download Station. If a remote attacker gains a user account, they can then exploit the vulnerability to read application data.

We have already fixed the vulnerability in the following version: Download Station 5.10.1.312 and later Download Station 5.11.2.321 and later

Threat Intelligence Overview

EPSS Score
0.4%
Top 65% exploitable
Prevalence
Medium
optional add-on app for widely-deployed QNAP NAS appliances, not universal
Social Media
1
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Server-Side Request Forgery exploits applications that fetch remote resources based on user-supplied URLs.

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