Cyber Resilience

CVE-2026-20270

Cisco Ios Xe 16.10.1 … 26.1.1a

Published
05 August 2026
Modified
12 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0025 17th percentile
Risk Priority 60 floored blend · peak EPSS

Summary

CVE-2026-20270 is a high-severity Incorrect Calculation (CWE-682) vulnerability in Cisco Ios Xe. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 17th 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-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The…

more

vulnerabilities tracked by CVE-2026-20270 are related to incorrect calculation issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-682.

CWE(s)
CWE-682

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

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CVE-2025-20155Same product: Cisco Ios Xe
CVE-2024-20313Same product: Cisco Ios Xe
CVE-2024-20306Same product: Cisco Ios Xe
CVE-2018-0151Same product: Cisco Ios Xe
CVE-2026-20268Same product: Cisco Ios Xe
CVE-2024-20434Same product: Cisco Ios Xe
CVE-2024-20464Same product: Cisco Ios Xe
CVE-2023-20072Same product: Cisco Ios Xe
CVE-2025-20197Same product: Cisco Ios Xe

Affected Assets

cisco
ios xe
16.10.1, 16.10.1a, 16.10.1b, 16.10.1c, 16.10.1d

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)
  • V15.2.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation directly exercises calculations and can discover incorrect or unintended results used in security decisions.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development processes and standards can enforce coding rules and tool usage that reduce introduction of calculation errors.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles applied during design and implementation can require verified algorithms and safe arithmetic that structurally avoid incorrect calculation results.

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 calculations via reviews, testing, and verification in security-critical code.

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 and acceptance can detect calculation flaws before deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates verification steps that catch incorrect calculations before they reach production.

A.8.26 Application security requirements partial match
prevents

Application security requirements can explicitly call for numeric accuracy and bounds checking.

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

Secure architecture principles include input validation and safe arithmetic design that reduce calculation errors.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prohibit unsafe arithmetic and require defensive checks against incorrect results.

References