CVE-2020-27631
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
- Record
CVE-2020-27631- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-330
- Updated
- 2026-11-02
CVE List No score
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
- Record
CVE-2020-27631- Updated
- 2026-11-02
EUVDEUVD-2020-20138 No score
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
- Record
EUVD-2020-20138- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-gvwh-h9wm-jvg4
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
- Record
GHSA-gvwh-h9wm-jvg4- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-330
- Updated
- 2026-11-02
OSV
In Oryx CycloneTCP 1.9.6, TCP ISNs are improperly random.
- Record
CVE-2020-27631- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-27631 is a critical vulnerability (CVSS 9.8) in Oryx-embedded Cyclonetcp, published October 10, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.08%, the 65th percentile. No source names a fixed version.