VulnerabilityPublished 25 Feb 2026

CVE-2026-20010: Cisco NX-OS Software · Buffer Access with Incorrect Length Value

Affects Cisco NX-OS SoftwareSource CVE Database V5

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Not known to be exploited · CVSS 7.4 High.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

7.4High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CiscoCisco NX-OS Software	Affected 10.3(1) – 10.4(2) 17 affected builds	Fixed in–
CiscoCisco NX-OS System Software in ACI Mode	Affected 16.0(2h) – 16.1(3g) 21 affected builds	Fixed in–
CiscoCisco Unified Computing System (Managed)	Affected 4.3(4b) – 4.3(6d) 13 affected builds	Fixed in–

AI-suggested

Apply official Cisco patches or software updates as soon as they become available for the affected NX-OS versions. Regularly monitor Cisco security advisories for updates related to this vulnerability.
Implement strict network segmentation and access control at Layer 2 to restrict LLDP traffic only to trusted devices and interfaces. Use VLAN segmentation and private VLANs to limit broadcast domains and reduce the risk of unauthorized Layer 2 adjacency.
Disable LLDP on interfaces where it is not required, especially on user-facing or untrusted ports, to minimize the attack surface.
Employ network monitoring and anomaly detection to identify unusual LLDP traffic patterns or unexpected device reloads that could indicate exploitation attempts.
Use port security features to limit the number of devices that can connect to a given switch port, reducing the chance of an attacker gaining adjacency.
Consider implementing control plane policing (CoPP) or rate limiting on LLDP packets to mitigate the impact of malformed or malicious LLDP frames.
Conduct regular security audits of network device configurations to ensure adherence to best practices for Layer 2 security and LLDP usage. These targeted mitigations go beyond generic advice by focusing on controlling Layer 2 access and LLDP exposure, which are critical given the attack vector.

Description

A vulnerability in the Link Layer Discovery Protocol (LLDP) feature of Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause the LLDP process to restart, which could cause an affected device to reload unexpectedly. This vulnerability is due to improper handling of specific fields in an LLDP frame. An attacker could exploit this vulnerability by sending a crafted LLDP packet to an interface of an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition. Note: LLDP is a Layer 2 link protocol. To exploit this vulnerability, an attacker would need to be directly connected to an interface of an affected device, either physically or logically (for example, through a Layer 2 Tunnel configured to transport the LLDP protocol).

Impact

The primary impact of CVE-2026-20010 is a denial of service (DoS) condition caused by an unexpected device reload. For organizations relying on Cisco NX-OS devices—commonly used in data centers, enterprise core networks, and service provider infrastructures—this can lead to significant network outages, loss of connectivity, and disruption of critical services. The vulnerability affects the availability of network infrastructure rather than confidentiality or integrity. In environments where high availability and uptime are critical, such as financial institutions, healthcare providers, and telecommunications, the impact can be severe, potentially causing operational downtime and financial losses. Additionally, the requirement for Layer 2 adjacency limits the attack surface but does not eliminate risk, especially in environments with shared physical infrastructure or misconfigured network segmentation. The vulnerability could also be leveraged as part of a broader attack chain to disrupt network operations or facilitate lateral movement by causing instability in network devices. Given the widespread deployment of Cisco NX-OS in key network segments globally, the potential for disruption is substantial if exploited.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n3kn9k_aci_lldp_dos-NdgRrrA3 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Feb 2026, 00:01 UTC

Technical details

References

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