CVE-2021-1389 json
Cisco IOS XR and Cisco NX-OS Software IPv6 Access Control List Bypass Vulnerability
published 2021-02-04 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-6856
- cvss
- 5.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.2%
- EPSS 1.2% chance of exploitation in 30 days, percentile 69%
- public exploits
- 0
- none known
Summary
A vulnerability in the IPv6 traffic processing of Cisco IOS XR Software and Cisco NX-OS Software for certain Cisco devices could allow an unauthenticated, remote attacker to bypass an IPv6 access control list (ACL) that is configured for an interface of an affected device. The vulnerability is due to improper processing of IPv6 traffic that is sent through an affected device. An attacker could exploit this vulnerability by sending crafted IPv6 packets that traverse the affected device. A successful exploit could allow the attacker to access resources that would typically be protected by the interface ACL.
Patch / fix
- cisco ios_xr 6.6.3
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
1.24% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N |
| NVD | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
| NVD | 2.0 | 6.4 | AV:N/AC:L/Au:N/C:P/I:P/A:N |
Affected products
- Cisco Cisco IOS XR Software
Classification
- Weakness
-
- CWE-284 Improper Access Control
- Technology feeds
References
Sources
- CVE List CVE-2021-1389
- NVD CVE-2021-1389
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