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CVE-2021-34809

26
FAUCET Score

CVE-2021-34809 is a command injection vulnerability affecting Synology Download Station versions prior to 3.8.16-3566. This flaw allows remote authenticated users to execute arbitrary code due to improper neutralization of special elements in a command within the task management component. With a CVSS score of 8.8 (High), this vulnerability presents a significant risk, as it can be exploited over the network with low privileges and no user interaction, leading to high impact on confidentiality, integrity, and availability. Despite its severity, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.8.16-3566CPE match
cpe:2.3:a:synology:download_station:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.9CRITICAL

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.1
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.93%
Probability of exploitation in next 30 days
EPSS Percentile
77.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0193 is in the 76th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

synology.com / security/advisory/Synology_SA_21_11
Vendor Advisory