VulnerabilityPublished 25 Feb 2026

CVE-2026-20048: Cisco NX-OS System Software in ACI Mode · Uncontrolled Memory Allocation

Affects Cisco NX-OS System Software in ACI ModeSource CVE Database V5

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Not known to be exploited · CVSS 7.7 High.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

7.7High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
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: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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 System Software in ACI Mode	Affected 15.2(1g) – 16.1(4h) 57 affected builds	Fixed in–

AI-suggested

Apply Cisco's security patches or software updates for NX-OS versions addressing this vulnerability as soon as they become available.
Restrict SNMP access strictly to trusted management stations and networks using access control lists (ACLs) and firewall rules to minimize exposure.
Enforce strong SNMP authentication by using SNMPv3 with robust user credentials and disable SNMPv1 and SNMPv2c where possible.
Regularly audit SNMP community strings and user accounts to ensure they are complex, unique, and rotated periodically.
Monitor SNMP traffic for unusual patterns such as repeated queries to specific MIBs that could indicate exploitation attempts.
Implement network segmentation to isolate management interfaces from general user networks.
Employ intrusion detection/prevention systems (IDS/IPS) capable of detecting anomalous SNMP activity.
Conduct regular vulnerability assessments and penetration testing focused on network management protocols.
Educate network administrators on secure SNMP configuration and the risks of credential exposure.
Maintain up-to-date inventory of affected devices and versions to prioritize remediation efforts effectively.

Description

A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper processing when parsing SNMP requests. An attacker could exploit this vulnerability by continuously sending SNMP queries to a specific MIB of an affected device. A successful exploit could allow the attacker to cause a kernel panic on the device, resulting in a reload and a DoS condition. Note: This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMPv1 or SNMPv2c, the attacker must have a valid read-only SNMP community string for the affected system. To exploit this vulnerability through SNMPv3, the attacker must have valid SNMP user credentials for the affected system.

Impact

The primary impact of CVE-2026-20048 is a denial of service condition on Cisco Nexus 9000 Series Fabric Switches operating in ACI mode. A successful exploit causes a kernel panic and forces the device to reload, leading to temporary loss of network connectivity and disruption of data center or enterprise network operations. Given the critical role of Nexus 9000 switches in data center fabrics and ACI deployments, this can result in significant operational downtime, affecting business continuity and potentially causing cascading failures in dependent systems. The vulnerability does not allow data exfiltration or modification, so confidentiality and integrity remain intact. However, the loss of availability in core network infrastructure can impact cloud services, enterprise applications, and critical communications. Organizations relying heavily on Cisco ACI for network automation and segmentation may face increased risk of service degradation or outages. The requirement for valid SNMP credentials limits exploitation to insiders or attackers who have already compromised SNMP authentication, but this does not eliminate the risk, especially in environments with weak SNMP credential management or exposed SNMP interfaces.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-dsnmp-cNN39Uh (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Feb 2026, 00:02 UTC

Technical details

References

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