Cisco NX-OS System Software in ACI Mode: Memory Allocation with Excessive Size Value
CVE-2026-20048 is a high-severity memory allocation with excessive size value vulnerability in Cisco NX-OS System Software in ACI Mode from Cisco, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected Cisco NX-OS System Software in ACI Mode versions: 15.2(1g); 15.2(2e); 15.2(2f), and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.34% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Cisco NX-OS System Software in ACI Mode you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco NX-OS System Software in ACI Mode | 15.2(1g); 15.2(2e); 15.2(2f); 15.2(2g); 15.2(2h); 15.2(3f); 15.2(3e); 15.2(3g); and 32 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H. Scored by CNA (cisco.com).
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Memory Allocation with Excessive Size Value
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
How developers prevent this class of flaw
- Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
- Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
More Memory Allocation with Excessive Size Value vulnerabilities (CWE-789)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Cisco NX-OS System Software in ACI Mode
- 9.8 Critical severity
- 8.6 High severity
- 8.6 High severity
- 8.6 High severity
- 9.8 Critical severity
- 8.8 High severity
Recent Memory Allocation with Excessive Size Value vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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