CVE-2021-1590
CVE-2021-1590 is a medium-severity vulnerability in Cisco Nx-os with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: Medium (CVSS 3.x base score 5.3)
- CVSS v2: 4.3
- EPSS exploit prediction: 2% (72nd percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-787
- Affected product: Cisco Nx-os
- Published:
- Last modified:
Description
A vulnerability in the implementation of the system login block-for command for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a login process to unexpectedly restart, causing a denial of service (DoS) condition. This vulnerability is due to a logic error in the implementation of the system login block-for command when an attack is detected and acted upon. An attacker could exploit this vulnerability by performing a brute-force login attack on an affected device. A successful exploit could allow the attacker to cause a login process to reload, which could result in a delay during authentication to the affected device.
Frequently asked questions
- What is CVE-2021-1590?
- A vulnerability in the implementation of the system login block-for command for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a login process to unexpectedly restart, causing a denial of service (DoS) condition. This vulnerability is due to a logic error in the implementation of the system login block-for command when an attack is detected and acted upon. An attacker could exploit this vulnerability by performing a brute-force login attack on an affected device. A successful exploit could allow the attacker to cause a login process to reload, which could result in a delay during authentication to the affected device.
- How severe is CVE-2021-1590?
- CVE-2021-1590 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
- Is CVE-2021-1590 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-1590?
- CVE-2021-1590 primarily affects Cisco Nx-os. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-1590?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2021-1590 published?
- CVE-2021-1590 was published on 2021-08-25 and last updated on 2026-06-17.
References
Affected products (3)
- cpe:2.3:o:cisco:nx-os:7.0\(3\)i4\(0.116\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:nx-os:7.3\(7\)n1\(1b\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:unified_computing_system:*:*:*:*:*:*:*:*
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