High-severity remote file read/write and DoS in Synology DSM, a widely deployed NAS OS used across enterprises and SMBs; impact and CVSS 9.8 warrant broad IT distribution.
CVE-2026-13639
Insufficient entropy in Synology DSM login enables remote file read/write and DoS.
Is CVE-2026-13639 being exploited?
Not confirmed. CVE-2026-13639 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.66% probability of exploitation in the next 30 days.
How severe is CVE-2026-13639?
CVE-2026-13639 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-13639?
Yes. A fix has been recorded for CVE-2026-13639. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-13639 affect?
CVE-2026-13639 affects Synology DiskStation Manager (DSM) versions before 7.2.1-69057-12, DSM before 7.2.2-72806-9, DSM before 7.3.2-86009-4, DSM before 7.4-90075. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-13639?
Upgrade DSM to the fixed versions immediately and restrict network access until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attackers can read/write arbitrary files and cause denial-of-service via weak entropy in DSM login, enabling data theft, device compromise, or service outage.
Immediate action required
- affected>= 7.4 and < 7.4-90075
- affected>= 7.3.2 and < 7.3.2-86009-4
- affected>= 7.2.2 and < 7.2.2-72806-9
- affected>= 7.2.1 and < 7.2.1-69057-12
- affected< 7.2.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
cisa ssvc
- exploitation
- none
- automatable
- yes
- technical impact
- total
Assessed by CISA 18 Sept 2026 (SSVC 2.0.3).
timeline
- 18 Sept 2026Published
- 18 Sept 2026CISA SSVC assessment: exploitation none · same day later
- 18 Sept 2026CVE record last updated · same day later
- 19 Sept 2026Analysed by vulneraibility.com · same day later
- Linksynology.com /en-global/security/advisory/Synology_SA_26_13
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.