CVE-2021-1590

mediumpriority · track · 21EPSS 0.014 · 71 %ileEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.35% (71st) EPSS
CVSS 4.3 · medium
Is it mine?
34 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-26

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.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedCisco NX-OS Software 7.3(0)D1(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(0)D1(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(0)DX(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(0)DY(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(1)D1(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(1)D1(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(1)DY(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(2)D1(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(2)D1(2) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(2)D1(3) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 7.3(2)D1(3a) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.1(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.1(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.1(1a) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.1(2) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.1(2a) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.2(1) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.2(1) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.2(2) when installed on Cisco MDS 9000 Multilayer Directors and Fabric Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco NX-OS Software 8.2(2) when installed on Cisco Nexus 7000 Series Switchescisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
  • FixedCisco Unified Computing System (Managed)cisco_csaf

    Cisco has released software updates that address this vulnerability.

    https://software.cisco.com
02

cvss

Technical severity, 0–10. One row per scoring source.

5.3
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 2.9
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lprimary · NVD / NIST USexploitability 3.9 · impact 1.4
v3.15.3mediumAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · FSTEC (BDU) RU
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · psirt@cisco.com USexploitability 3.9 · impact 1.4
v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:Usecondary · CVSS-BT (t0sche)
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · Cisco PSIRT US
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-787USCWE-787US
05

affected products (34)

Products and version ranges known to be affected.

showing 20 of 34
06

advisories (1)

Vendor and ecosystem advisories describing this.

  • cisco-sa-nxos-login-blockfor-RwjGVEcuCisco NX-OS Software system login block-for Denial of Service Vulnerability2021-08-25csaf · cisco_csafUS

    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. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of the August 2021 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: August 2021 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74640"].

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisco_csafNVDCVE.orgMITRE
published 2021-08-25modified 2026-06-17
09

references (5)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan