In FNET 4.6.3, TCP ISNs are improperly random.
Priority MEDIUM 49CWE-330Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
In FNET 4.6.3, TCP ISNs are improperly random.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00871 59th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2020-27633
- 2026-10-03 Alias added: GHSA-5m6v-343g-pr27
References
More Butok Fnet vulnerabilities
- TI-2020-14924 An issue was discovered in FNET through 4.6.4. CVSS 3.1CRITICAL 9.1
- TI-2020-13227 An issue was discovered in FNET through 4.6.4. CVSS 3.1CRITICAL 9.1
- TI-2020-13229 An issue was discovered in FNET through 4.6.4. CVSS 3.1HIGH 7.5
- TI-2020-13228 An issue was discovered in FNET through 4.6.4. CVSS 3.1HIGH 7.5
- TI-2020-13230 An issue was discovered in FNET through 4.6.4. CVSS 3.1MEDIUM 5.3
Sources
- CVE-2020-27633 · CVE Program
- CVE-2020-27633 · NVD
- FIRST EPSS
- GHSA-5m6v-343g-pr27 · GitHub Advisory Database · CC BY 4.0
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