Cybersecurity professionals consider CVE-2021-1523 an immediate threat requiring urgent mitigation.
Status: Modified
Last updated: 🕠 21 Nov 2024, 05:44 UTC
Originally published on: 🕖 25 Aug 2021, 19:15 UTC
Time between publication and last update: 1183 days
CVSS Release: version 3
ykramarz@cisco.com
Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CVE-2021-1523: A vulnerability in Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, remote attacker to cause a queue wedge on a leaf switch, which could result in critical control plane traffic to the device being dropped. This could result in one or more leaf switches being removed from the fabric. This vulnerability is due to mishandling of ingress TCP traffic to a specific port. An attacker could exploit this vulnerability by sending a stream of TCP packets to a specific port on a Switched Virtual Interface (SVI) configured on the device. A successful exploit could allow the attacker to cause a specific packet queue to queue network buffers but never process them, leading to an eventual queue wedge. This could cause control plane traffic to be dropped, resulting in a denial of service (DoS) condition where the leaf switches are unavailable. Note: This vulnerability requires a manual intervention to power-cycle the device to recover.
The exploitability of CVE-2021-1523 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
With low attack complexity and no required privileges, CVE-2021-1523 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2021-1523, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2021-1523, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.16% (probability of exploit)
EPSS Percentile: 53.85%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 46.15% of others.
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