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Vulnerability record · CVE-2021-34739 · published 4 November 2021

CVE-2021-34739: Cisco sf250-24 firmware insufficient session expiration vulnerability

Cisco · Sf250 24 Firmware

A vulnerability in the web-based management interface of multiple Cisco Small Business Series Switches could allow an unauthenticated, remote attacker to replay valid user session credentials and gain unauthorized access to the web-based management interface of an affected device. This vulnerability is due to insufficient expiration of session credentials. An attacker could exploit this vulnerability by conducting a man-in-the-middle attack against an affected device to intercept valid session credentials and then replaying the intercepted credentials toward the same device at a later time. A successful exploit could allow the attacker to access the web-based management interface with administrator privileges.

8.1 CVSS 3.1 High EPSS 1.7% · top 23.9% CWE-613 · Insufficient session expiration
8.1CVSS 3.1 base score, v2 6.8
1.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
150Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability in the web-based management interface of multiple Cisco Small Business Series Switches could allow an unauthenticated, remote attacker to replay valid user session credentials and gain unauthorized access to the web-based management interface of an affected device. This vulnerability is due to insufficient expiration of session credentials. An attacker could exploit this vulnerability by conducting a man-in-the-middle attack against an affected device to intercept valid session credentials and then replaying the intercepted credentials toward the same device at a later time. A successful exploit could allow the attacker to access the web-based management interface with administrator privileges.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

150 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-switches-tokens-UzwpR4e5 Vendor Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smb-switches-tokens-UzwpR4e5 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.2CVE-2024-20263Cisco cbs250-8t-d firmware improper access control vulnerabilityA vulnerability with the access control list (ACL) management within a stacked switch configuration of Cisco Business 250 Series Smart Switches and B…EPSS 0.45%

Source: NIST National Vulnerability Database (record CVE-2021-34739), CISA KEV, FIRST EPSS (scores of 2026-10-09). This page is refreshed as NVD updates the record.