What’s Vulnerable › Vulnerabilities
CVE-2021-40127: Cisco Small Business 200, 300, and 500 Series Switches Web-Based Management Interface Denial of Service Vulnerability
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 1.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2021-11-04 · updated 2026-06-17
- Weakness: CWE-20
Description
A vulnerability in the web-based management interface of Cisco Small Business 200 Series Smart Switches, Cisco Small Business 300 Series Managed Switches, and Cisco Small Business 500 Series Stackable Managed Switches could allow an unauthenticated, remote attacker to render the web-based management interface unusable, resulting in a denial of service (DoS) condition. This vulnerability is due to improper validation of HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to cause a permanent invalid redirect for requests sent to the web-based management interface of the device, resulting in a DoS condition.
Affected products
- Cisco Sf200-24 Firmware: all versions
- Cisco Sf200-24Fp Firmware: all versions
- Cisco Sf200-24P Firmware: all versions
- Cisco Sf200-48 Firmware: all versions
- Cisco Sf200-48P Firmware: all versions
- Cisco Sf200E-24 Firmware: all versions
- Cisco Sf200E-24P Firmware: all versions
- Cisco Sf200E-48 Firmware: all versions
- Cisco Sf200E-48P Firmware: all versions
- Cisco Sf300-08 Firmware: 1.4.11.02
- Cisco Sf300-24 Firmware: 1.4.11.02
- Cisco Sf300-24Mp Firmware: 1.4.11.02
- Cisco Sf300-24P Firmware: 1.4.11.02
- Cisco Sf300-24Pp Firmware: 1.4.11.02
- Cisco Sf300-48 Firmware: 1.4.11.02
- Cisco Sf300-48P Firmware: 1.4.11.02
- Cisco Sf300-48Pp Firmware: 1.4.11.02
- Cisco Sf302-08 Firmware: 1.4.11.02
- Cisco Sf302-08Mp Firmware: 1.4.11.02
- Cisco Sf302-08Mpp Firmware: 1.4.11.02
- Cisco Sf302-08P Firmware: 1.4.11.02
- Cisco Sf302-08Pp Firmware: 1.4.11.02
- Cisco Sf500-24 Firmware: all versions
- Cisco Sf500-24Mp Firmware: all versions
- Cisco Sf500-24P Firmware: all versions
- Cisco Sf500-48 Firmware: all versions
- Cisco Sf500-48Mp Firmware: all versions
- Cisco Sf500-48P Firmware: all versions
- Cisco Sg200-08 Firmware: all versions
- Cisco Sg200-08P Firmware: all versions
References
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-switches-web-dos-xMyFFkt8
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-switches-web-dos-xMyFFkt8
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