DiskStation Manager (DSM): Insufficient Entropy
CVE-2026-13639 is a critical-severity insufficient entropy vulnerability in DiskStation Manager (DSM) from Synology, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 7.4-90075, 7.3.2-86009-4, 7.2.2-72806-9 as the first without the flaw, so updating DiskStation Manager (DSM) to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.66% chance of exploitation within 30 days, higher than 52% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update DiskStation Manager (DSM) to 7.4-90075 or 7.3.2-86009-4 or 7.2.2-72806-9 or 7.2.1-69057-12, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Synology | DiskStation Manager (DSM) | 7.4 up to, but not including, 7.4-90075; 7.3.2 up to, but not including, 7.3.2-86009-4; 7.2.2 up to, but not including, 7.2.2-72806-9; 7.2.1 up to, but not including, 7.2.1-69057-12 | 7.4-90075, 7.3.2-86009-4, 7.2.2-72806-9, 7.2.1-69057-12 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (synology.com).
Official description
An insufficient entropy vulnerability in login logic in Synology DiskStation Manager (DSM) before 7.2.1-69057-12, 7.2.2-72806-9, 7.3.2-86009-4 and 7.4-90075 allows remote attackers to read or write arbitrary files and conduct denial-of-service attacks.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Insufficient Entropy
The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others.
How developers prevent this class of flaw
- Determine the necessary entropy to adequately provide for randomness and predictability. This can be achieved by increasing the number of bits of objects such as keys and seeds.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
References
Other references
Other vulnerabilities in DiskStation Manager (DSM)
- 8.6 High severity
- 8.1 High severity
- 9.8 Critical severity
- 7.2 High severity
- 8.8 High severity
- 8.1 High severity
Recent Insufficient Entropy vulnerabilities
- 8.1 High severity
- 7.4 High severity
- 9.0 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.1 High severity
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