CVE-2021-34739
Cisco Small Business Series Switches Session Credentials Replay Vulnerability
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used 8.1
Cisco Small Business Series Switches Session Credentials Replay Vulnerability
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.
- Record
CVE-2021-34739- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-613
- Updated
- 2026-11-02
EUVDEUVD-2021-21389 8.1
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.
- Record
EUVD-2021-21389- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-5fmw-qrmv-x2mwNo score
A vulnerability in the web-based management interface of multiple Cisco Small Business Series...
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.
- Record
GHSA-5fmw-qrmv-x2mw- Weakness
- CWE-613
- Updated
- 2026-11-02
NVD 8.1
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.
- Record
CVE-2021-34739- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 6.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-613
- Updated
- 2026-11-02
Affected products
- cisco cbs250-16p-2g firmware
- cisco cbs250-16t-2g firmware
- cisco cbs250-24fp-4g firmware
- cisco cbs250-24fp-4x firmware
- cisco cbs250-24p-4g firmware
- cisco cbs250-24p-4x firmware
- cisco cbs250-24pp-4g firmware
- cisco cbs250-24t-4g firmware
- cisco cbs250-24t-4x firmware
- cisco cbs250-48p-4g firmware
- cisco cbs250-48p-4x firmware
- cisco cbs250-48pp-4g firmware
Show 198 moreShow less
- cisco cbs250-48t-4g firmware
- cisco cbs250-48t-4x firmware
- cisco cbs250-8fp-e-2g firmware
- cisco cbs250-8p-e-2g firmware
- cisco cbs250-8pp-d firmware
- cisco cbs250-8pp-e-2g firmware
- cisco cbs250-8t-d firmware
- cisco cbs250-8t-e-2g firmware
- cisco cbs350-12np-4x firmware
- cisco cbs350-12xs firmware
- cisco cbs350-12xt firmware
- cisco cbs350-16fp-2g firmware
- cisco cbs350-16p-2g firmware
- cisco cbs350-16p-e-2g firmware
- cisco cbs350-16t-2g firmware
- cisco cbs350-16t-e-2g firmware
- cisco cbs350-16xts firmware
- cisco cbs350-24fp-4g firmware
- cisco cbs350-24fp-4x firmware
- cisco cbs350-24mgp-4x firmware
- cisco cbs350-24ngp-4x firmware
- cisco cbs350-24p-4g firmware
- cisco cbs350-24p-4x firmware
- cisco cbs350-24s-4g firmware
- cisco cbs350-24t-4g firmware
- cisco cbs350-24t-4x firmware
- cisco cbs350-24xs firmware
- cisco cbs350-24xt firmware
- cisco cbs350-24xts firmware
- cisco cbs350-48fp-4g firmware
- cisco cbs350-48fp-4x firmware
- cisco cbs350-48ngp-4x firmware
- cisco cbs350-48p-4g firmware
- cisco cbs350-48p-4x firmware
- cisco cbs350-48t-4g firmware
- cisco cbs350-48t-4x firmware
- cisco cbs350-48xt-4x firmware
- cisco cbs350-8fp-2g firmware
- cisco cbs350-8fp-e-2g firmware
- cisco cbs350-8mgp-2x firmware
- cisco cbs350-8mp-2x firmware
- cisco cbs350-8p-2g firmware
- cisco cbs350-8p-e-2g firmware
- cisco cbs350-8s-e-2g firmware
- cisco cbs350-8t-e-2g firmware
- cisco cbs350-8xt firmware
- cisco small business smart and managed switches
- cisco esw2-350g-52 firmware
- cisco esw2-350g-52dc firmware
- cisco esw2-550x-48 firmware
- cisco esw2-550x-48dc firmware
- cisco sf200-24 firmware
- cisco sf200-24fp firmware
- cisco sf200-24p firmware
- cisco sf200-48 firmware
- cisco sf200-48p firmware
- cisco sf250-08 firmware
- cisco sf250-08hp firmware
- cisco sf250-10p firmware
- cisco sf250-18 firmware
- cisco sf250-24 firmware
- cisco sf250-24p firmware
- cisco sf250-26 firmware
- cisco sf250-26hp firmware
- cisco sf250-26p firmware
- cisco sf250-48 firmware
- cisco sf250-48hp firmware
- cisco sf250-50 firmware
- cisco sf250-50hp firmware
- cisco sf250-50p firmware
- cisco sf250x-24 firmware
- cisco sf250x-24p firmware
- cisco sf250x-48 firmware
- cisco sf250x-48p firmware
- cisco sf300-08 firmware
- cisco sf300-24 firmware
- cisco sf300-24mp firmware
- cisco sf300-24p firmware
- cisco sf300-24pp firmware
- cisco sf300-48 firmware
- cisco sf300-48p firmware
- cisco sf300-48pp firmware
- cisco sf302-08 firmware
- cisco sf302-08mp firmware
- cisco sf302-08mpp firmware
- cisco sf302-08p firmware
- cisco sf302-08pp firmware
- cisco sf350-08 firmware
- cisco sf350-10 firmware
- cisco sf350-10mp firmware
- cisco sf350-10p firmware
- cisco sf350-10sfp firmware
- cisco sf350-20 firmware
- cisco sf350-24 firmware
- cisco sf350-24mp firmware
- cisco sf350-24p firmware
- cisco sf350-28 firmware
- cisco sf350-28mp firmware
- cisco sf350-28p firmware
- cisco sf350-28sfp firmware
- cisco sf350-48 firmware
- cisco sf350-48p firmware
- cisco sf350-52 firmware
- cisco sf350-52mp firmware
- cisco sf350-52p firmware
- cisco sf350-8mp firmware
- cisco sf350-8pd firmware
- cisco sf352-08 firmware
- cisco sf352-08mp firmware
- cisco sf352-08p firmware
- cisco sf355-10p firmware
- cisco sf500-24 firmware
- cisco sf500-24mp firmware
- cisco sf500-24p firmware
- cisco sf500-48 firmware
- cisco sf500-48mp firmware
- cisco sf500-48p firmware
- cisco sf550x-24 firmware
- cisco sf550x-24mp firmware
- cisco sf550x-24p firmware
- cisco sf550x-48 firmware
- cisco sf550x-48mp firmware
- cisco sf550x-48p firmware
- cisco sg200-08 firmware
- cisco sg200-08p firmware
- cisco sg200-10fp firmware
- cisco sg200-18 firmware
- cisco sg200-26 firmware
- cisco sg200-26fp firmware
- cisco sg200-26p firmware
- cisco sg200-50 firmware
- cisco sg200-50fp firmware
- cisco sg200-50p firmware
- cisco sg300-10 firmware
- cisco sg300-10mp firmware
- cisco sg300-10mpp firmware
- cisco sg300-10p firmware
- cisco sg300-10pp firmware
- cisco sg300-10sfp firmware
- cisco sg300-20 firmware
- cisco sg300-28 firmware
- cisco sg300-28mp firmware
- cisco sg300-28p firmware
- cisco sg300-28pp firmware
- cisco sg300-28sfp firmware
- cisco sg300-52 firmware
- cisco sg300-52mp firmware
- cisco sg300-52p firmware
- cisco sg350x-12pmv firmware
- cisco sg350x-24 firmware
- cisco sg350x-24mp firmware
- cisco sg350x-24p firmware
- cisco sg350x-24pd firmware
- cisco sg350x-24pv firmware
- cisco sg350x-48 firmware
- cisco sg350x-48mp firmware
- cisco sg350x-48p firmware
- cisco sg350x-48pv firmware
- cisco sg350x-8pmd firmware
- cisco sg350xg-24f firmware
- cisco sg350xg-24t firmware
- cisco sg350xg-2f10 firmware
- cisco sg350xg-48t firmware
- cisco sg500-28 firmware
- cisco sg500-28mpp firmware
- cisco sg500-28p firmware
- cisco sg500-52 firmware
- cisco sg500-52mp firmware
- cisco sg500-52p firmware
- cisco sg500x-24 firmware
- cisco sg500x-24mpp firmware
- cisco sg500x-24p firmware
- cisco sg500x-48 firmware
- cisco sg500x-48mp firmware
- cisco sg500x-48p firmware
- cisco sg500xg-8f8t firmware
- cisco sg550x-24 firmware
- cisco sg550x-24mp firmware
- cisco sg550x-24mpp firmware
- cisco sg550x-24p firmware
- cisco sg550x-48 firmware
- cisco sg550x-48mp firmware
- cisco sg550x-48p firmware
- cisco sg550xg-24f firmware
- cisco sg550xg-24t firmware
- cisco sg550xg-48t firmware
- cisco sg550xg-8f8t firmware
- cisco sx350x-08 firmware
- cisco sx350x-12 firmware
- cisco sx350x-24 firmware
- cisco sx350x-24f firmware
- cisco sx350x-52 firmware
- cisco sx550x-12f firmware
- cisco sx550x-16ft firmware
- cisco sx550x-24 firmware
- cisco sx550x-24f firmware
- cisco sx550x-24ft firmware
- cisco sx550x-52 firmware
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-34739 is a high vulnerability (CVSS 8.1) in Cisco Cbs250-16p-2g Firmware, published November 4, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.67%, the 77th percentile. No source names a fixed version.