CVE-2021-34793
HIGHDescription
A vulnerability in the TCP Normalizer of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software operating in transparent mode could allow an unauthenticated, remote attacker to poison MAC address tables, resulting in a denial of service (DoS) vulnerability. This vulnerability is due to incorrect handling of certain TCP segments when the affected device is operating in transparent mode. An attacker could exploit this vulnerability by sending a crafted TCP segment through an affected device. A successful exploit could allow the attacker to poison the MAC address tables in adjacent devices, resulting in network disruption.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 48% of all known CVEs.
References
Related Vulnerabilities
Other CWE-924 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-3596 | Critical | 9.0 | 15% | - | Fix |
| CVE-2018-14526 | Medium | 6.5 | 1.5% | - | Fix |
| CVE-2021-21390 | Medium | 6.5 | 0.9% | - | Fix |
| CVE-2022-3166 | High | 7.5 | 0.7% | - | - |
| CVE-2021-3716 | Low | 3.1 | 0.6% | - | Fix |
| CVE-2024-43450 | High | 7.5 | 0.6% | - | Fix |
Common questions
How do I fix CVE-2021-34793?
Published advisories record a fix for 3 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-34793 being actively exploited?
Not that we know of. CVE-2021-34793 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.65% is the estimated probability that it will be exploited in the next 30 days. That is higher than 48% of all scored CVEs.
How severe is CVE-2021-34793?
CVE-2021-34793 has a CVSS v3 base score of 8.6, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-34793 affect?
Published advisories record a fix for adaptive security appliance (NVD), adaptive security appliance software (NVD), firepower threat defense (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.