Cyber Resilience

CVE-2026-20033

Published
25 February 2026
Modified
15 April 2026
CVSS Score v3.1 7.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0016 5th percentile
Risk Priority 52 floored blend · peak EPSS

Summary

CVE-2026-20033 is a high-severity Buffer Access with Incorrect Length Value (CWE-805) vulnerability in Cisco Nexus (inferred from references). Its CVSS base score is 7.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-20033 is a vulnerability affecting Cisco Nexus 9000 Series Fabric Switches operating in ACI mode. The issue arises from insufficient validation when processing specific Ethernet frames on the out-of-band (OOB) management interface, which could allow an unauthenticated adjacent attacker to trigger a denial of service (DoS) condition. Published on 2026-02-25, it carries a CVSS v3.1 base score of 7.4 (AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H) and maps to CWE-805.

An adjacent attacker can exploit this vulnerability by sending a crafted Ethernet frame to the OOB management interface of an affected device. Successful exploitation causes the device to reload unexpectedly, leading to a DoS condition. Only the OOB management interface is impacted.

The Cisco Security Advisory provides details on mitigation and patches: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-cpdos-qLsv6pFD.

EU & UK References

Vulnerability Data

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient validation when processing specific…

more

Ethernet frames. An attacker could exploit this vulnerability by sending a crafted Ethernet frame to the management interface of an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. Note: Only the out-of-band (OOB) management interface is affected.

CWE(s)
CWE-805

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-20315Shared CWE-805
CVE-2026-12549Shared CWE-805
CVE-2025-7048Shared CWE-805
CVE-2025-36461Shared CWE-805
CVE-2023-5396Shared CWE-805
CVE-2025-20202Shared CWE-805
CVE-2026-0716Shared CWE-805
CVE-2026-6245Shared CWE-805
CVE-2026-1767Shared CWE-805
CVE-2025-36462Shared CWE-805

Affected Assets

Cisco
Nexus
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.4.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (including fuzzing and static analysis) directly finds incorrect length values used in sequential buffer accesses.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require explicit bounds checking and correct length calculations when performing buffer operations.

SI-10 Information Input Validation partial match

Input validation rejects or corrects malformed length values supplied from external sources before they reach buffer operations.

SI-16 Memory Protection partial match

Memory protection mechanisms limit the blast radius when an incorrect length value causes an out-of-bounds access.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent incorrect-length buffer operations via safe APIs, reviews, and testing.

ID.RA-01 partial match
prevents

Vulnerability identification can discover buffer-length flaws but does not prevent their introduction.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect out-of-bounds accesses, but does not guarantee prevention.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates buffer-safety practices that directly prevent incorrect length values.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify buffer-size validation, but do not prescribe implementation details.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage bounds-checked APIs, yet leave concrete coding decisions to developers.

A.8.28 Secure coding partial match
prevents

Secure coding explicitly requires correct buffer-length handling, eliminating CWE-805 when followed.

References