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CVE-2021-27646

30
FAUCET Score

CVE-2021-27646 is a critical Use After Free vulnerability affecting Synology DiskStation Manager (DSM) versions prior to 6.2.3-25426-3. This flaw allows unauthenticated remote attackers to execute arbitrary code on affected devices by sending specially crafted web requests. With a CVSS score of 9.8, it poses a severe risk due to its network-based attack vector, low attack complexity, and complete compromise of confidentiality, integrity, and availability. Despite its high severity, there is 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
< 6.2.3-25426-3CPE matchmatch criteria
cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.79%
Probability of exploitation in next 30 days
EPSS Percentile
88.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0379 is in the 82nd percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 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_20_26
Vendor Advisory
zerodayinitiative.com / advisories/ZDI-21-339
Not Applicable
zerodayinitiative.com / advisories/ZDI-21-340
Third Party AdvisoryVDB Entry