CVE-2021-1387 json
Cisco NX-OS Software IPv6 Netstack Denial of Service Vulnerability
published 2021-02-24 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-6854
- cvss
- 8.6
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.4%
- EPSS 1.4% chance of exploitation in 30 days, percentile 72%
- public exploits
- 0
- none known
Summary
A vulnerability in the network stack of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because the software improperly releases resources when it processes certain IPv6 packets that are destined to an affected device. An attacker could exploit this vulnerability by sending multiple crafted IPv6 packets to an affected device. A successful exploit could cause the network stack to run out of available buffers, impairing operations of control plane and management plane protocols and resulting in a DoS condition. Manual intervention would be required to restore normal operations on the affected device. For more information about the impact of this vulnerability, see the Details section of this advisory.
Patch / fix
- cisco unified_computing_system 4.0\(4k\), 4.1\(1e\)
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
1.42% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVD | 3.1 | 8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:N/A:P |
Affected products
- Cisco Cisco NX-OS Software
Classification
- Weakness
-
- CWE-401 Missing Release of Memory after Effective Lifetime
References
Sources
- CVE List CVE-2021-1387
- NVD CVE-2021-1387
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