Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-20169 is a high-severity Access of Memory Location After End of Buffer (CWE-788) vulnerability in Cisco Nx-Os. Its CVSS base score is 7.4 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 24th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-24348
Vulnerability Data
A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco NX-OS Software for the Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS…
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process to unexpectedly restart, which could cause an affected device to reload. This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition due to the unexpected restart of the IS-IS process, which could cause the affected device to reload. Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2 adjacent to the affected device.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Directly implements checks on information inputs to reject invalid data before processing.
Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.
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.
Secure SDLC practices directly require bounds checking and input validation that prevent out-of-bounds buffer accesses.
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.8.25 mandates secure SDLC practices (secure coding guidelines, security requirements, checkpoints, testing including code scans and penetration tests, developer training) that reach buffer management and can stop many out-of-bounds accesses from reaching production, but leaves a bounded remainder (e.g. defects that slip past imperfect testing, non-software systems, or outsourced development without full assurance).
A.8.26 explicitly lists resilience against buffer overflow (and SQLi) as one of the application security requirements to identify/address during development or acquisition; well-implemented, this reaches a minority slice of CWE-788 instances (those caught in requirements/risk assessment) but leaves most implementation-level buffer errors untouched.
A.8.27 mandates security-by-design principles (defense-in-depth, least privilege, fail securely, distrust external input, hardening, zero-trust verification) plus design reviews against known attack patterns, which can stop buffer overruns from being exploitable in many cases but leaves a bounded remainder (e.g. unsafe legacy code, unsafe third-party libraries, or implementation errors that slip past reviews).
Secure coding standards directly forbid writing or reading past buffer ends.
Security testing in development can detect buffer-overrun defects before release.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-20, a class-level weakness, and none of its children carries one either.