CVE-2026-20271
Cisco Ios Xe 16.10.1 … 26.1.1a
Raw vector
CVSS:3.1/AV:N/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-2026-20271 is a high-severity Insufficient Control Flow Management (CWE-691) vulnerability in Cisco Ios Xe. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Process Injection (T1055); ranked at the 20th 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 SC-2 (Separation of System and User Functionality) and SC-3 (Security Function Isolation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-53457
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-2026-20271 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-691.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 1 hardening rule · 1 OS baseline
—
Mitigating Controls (NIST 800-53 r5) AI
Separating user and system functionality structurally limits unexpected control-flow transfers between domains.
Isolating security functions prevents control-flow tampering that would otherwise bypass or alter security decisions.
Process isolation keeps execution domains separate so one process cannot hijack another's control flow.
Memory protection blocks unauthorized code execution that would modify control flow at runtime.
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 activities such as static analysis, code review, and testing directly prevent control-flow weaknesses while also addressing many other coding defects.
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.
Secure development life cycle mandates structured control-flow design and review that directly reduces unexpected flow manipulation.
Secure system architecture and engineering principles require explicit control-flow integrity mechanisms and error-handling paths.
Secure coding standards explicitly forbid constructs that allow unintended control-flow changes such as missing breaks or unsafe jumps.
Security testing in development and acceptance can detect control-flow weaknesses but does not itself implement preventive controls.
Change management reduces introduction of control-flow defects through controlled updates but does not address the weakness directly.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).
Windows 10 (1 rule)
- V-220726 Data Execution Prevention (DEP) must be configured to at least OptOut. prevents CWE-691