{"id":"CVE-2026-20271","title":"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","summary":"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 …","severity":"high","cvss":8.6,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","cwe":["CWE-691"],"vendor":"cisco","product":"ios_xe","affected":["ios_xe = 16.6.2","ios_xe = 16.6.3","ios_xe = 16.6.4","ios_xe = 16.6.4a","ios_xe = 16.6.4s","ios_xe = 16.6.5","ios_xe = 16.6.5a","ios_xe = 16.6.5b","ios_xe = 16.6.6","ios_xe = 16.6.7","ios_xe = 16.6.7a","ios_xe = 16.6.8","ios_xe = 16.6.9","ios_xe = 16.6.10","ios_xe = 16.7.1","ios_xe = 16.7.1a","ios_xe = 16.7.1b","ios_xe = 16.7.2","ios_xe = 16.7.3","ios_xe = 16.7.4","ios_xe = 16.8.1","ios_xe = 16.8.1a","ios_xe = 16.8.1b","ios_xe = 16.8.1c","ios_xe = 16.8.1d","ios_xe = 16.8.1e","ios_xe = 16.8.1s","ios_xe = 16.8.2","ios_xe = 16.8.3","ios_xe = 16.9.1","ios_xe = 16.9.1a","ios_xe = 16.9.1b","ios_xe = 16.9.1c","ios_xe = 16.9.1d","ios_xe = 16.9.1s","ios_xe = 16.9.2","ios_xe = 16.9.2a","ios_xe = 16.9.2s","ios_xe = 16.9.3","ios_xe = 16.9.3a","ios_xe = 16.9.3h","ios_xe = 16.9.3s","ios_xe = 16.9.4","ios_xe = 16.9.4c","ios_xe = 16.9.5","ios_xe = 16.9.5f","ios_xe = 16.9.6","ios_xe = 16.9.7","ios_xe = 16.9.8","ios_xe = 16.9.8a","ios_xe = 16.9.8b","ios_xe = 16.10.1","ios_xe = 16.10.1a","ios_xe = 16.10.1b","ios_xe = 16.10.1c","ios_xe = 16.10.1d","ios_xe = 16.10.1e","ios_xe = 16.10.1f","ios_xe = 16.10.1g","ios_xe = 16.10.1s","ios_xe = 16.10.2","ios_xe = 16.10.3","ios_xe = 16.11.1","ios_xe = 16.11.1a","ios_xe = 16.11.1b","ios_xe = 16.11.1c","ios_xe = 16.11.1s","ios_xe = 16.11.2","ios_xe = 16.12.1","ios_xe = 16.12.1a","ios_xe = 16.12.1c","ios_xe = 16.12.1s","ios_xe = 16.12.1t","ios_xe = 16.12.1w","ios_xe = 16.12.1x","ios_xe = 16.12.1y","ios_xe = 16.12.1z","ios_xe = 16.12.1z1","ios_xe = 16.12.1z2","ios_xe = 16.12.2","ios_xe = 16.12.2a","ios_xe = 16.12.2s","ios_xe = 16.12.2t","ios_xe = 16.12.3","ios_xe = 16.12.3a","ios_xe = 16.12.3s","ios_xe = 16.12.4","ios_xe = 16.12.4a","ios_xe = 16.12.5","ios_xe = 16.12.5a","ios_xe = 16.12.5b","ios_xe = 16.12.6","ios_xe = 16.12.6a","ios_xe = 16.12.7","ios_xe = 16.12.8","ios_xe = 16.12.9","ios_xe = 16.12.10","ios_xe = 16.12.10a","ios_xe = 16.12.11","ios_xe = 16.12.12"],"published":"2026-08-05","updated":"2026-08-14","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-20271","references":[{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxe-V8NMuMZJ","label":"psirt@cisco.com"},{"url":"https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://software.cisco.com"}],"tags":["nvd","csaf","vendor-advisory","cisco"],"epss":0.00277,"epssPercentile":0.20378,"ingestedAt":"2026-08-15T17:27:27.967Z","slug":"CVE-2026-20271","body":"## Overview\n\nAs 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.\r\n\r\nThe 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.\r\n \n\n## Affected\n\n- `ios_xe = 16.6.2`\n- `ios_xe = 16.6.3`\n- `ios_xe = 16.6.4`\n- `ios_xe = 16.6.4a`\n- `ios_xe = 16.6.4s`\n- `ios_xe = 16.6.5`\n- `ios_xe = 16.6.5a`\n- `ios_xe = 16.6.5b`\n- `ios_xe = 16.6.6`\n- `ios_xe = 16.6.7`\n- `ios_xe = 16.6.7a`\n- `ios_xe = 16.6.8`\n- `ios_xe = 16.6.9`\n- `ios_xe = 16.6.10`\n- `ios_xe = 16.7.1`\n- `ios_xe = 16.7.1a`\n- `ios_xe = 16.7.1b`\n- `ios_xe = 16.7.2`\n- `ios_xe = 16.7.3`\n- `ios_xe = 16.7.4`\n- `ios_xe = 16.8.1`\n- `ios_xe = 16.8.1a`\n- `ios_xe = 16.8.1b`\n- `ios_xe = 16.8.1c`\n- `ios_xe = 16.8.1d`\n- `ios_xe = 16.8.1e`\n- `ios_xe = 16.8.1s`\n- `ios_xe = 16.8.2`\n- `ios_xe = 16.8.3`\n- `ios_xe = 16.9.1`\n- `ios_xe = 16.9.1a`\n- `ios_xe = 16.9.1b`\n- `ios_xe = 16.9.1c`\n- `ios_xe = 16.9.1d`\n- `ios_xe = 16.9.1s`\n- `ios_xe = 16.9.2`\n- `ios_xe = 16.9.2a`\n- `ios_xe = 16.9.2s`\n- `ios_xe = 16.9.3`\n- `ios_xe = 16.9.3a`\n- `ios_xe = 16.9.3h`\n- `ios_xe = 16.9.3s`\n- `ios_xe = 16.9.4`\n- `ios_xe = 16.9.4c`\n- `ios_xe = 16.9.5`\n- `ios_xe = 16.9.5f`\n- `ios_xe = 16.9.6`\n- `ios_xe = 16.9.7`\n- `ios_xe = 16.9.8`\n- `ios_xe = 16.9.8a`\n- `ios_xe = 16.9.8b`\n- `ios_xe = 16.10.1`\n- `ios_xe = 16.10.1a`\n- `ios_xe = 16.10.1b`\n- `ios_xe = 16.10.1c`\n- `ios_xe = 16.10.1d`\n- `ios_xe = 16.10.1e`\n- `ios_xe = 16.10.1f`\n- `ios_xe = 16.10.1g`\n- `ios_xe = 16.10.1s`\n- `ios_xe = 16.10.2`\n- `ios_xe = 16.10.3`\n- `ios_xe = 16.11.1`\n- `ios_xe = 16.11.1a`\n- `ios_xe = 16.11.1b`\n- `ios_xe = 16.11.1c`\n- `ios_xe = 16.11.1s`\n- `ios_xe = 16.11.2`\n- `ios_xe = 16.12.1`\n- `ios_xe = 16.12.1a`\n- `ios_xe = 16.12.1c`\n- `ios_xe = 16.12.1s`\n- `ios_xe = 16.12.1t`\n- `ios_xe = 16.12.1w`\n- `ios_xe = 16.12.1x`\n- `ios_xe = 16.12.1y`\n- `ios_xe = 16.12.1z`\n- `ios_xe = 16.12.1z1`\n- `ios_xe = 16.12.1z2`\n- `ios_xe = 16.12.2`\n- `ios_xe = 16.12.2a`\n- `ios_xe = 16.12.2s`\n- `ios_xe = 16.12.2t`\n- `ios_xe = 16.12.3`\n- `ios_xe = 16.12.3a`\n- `ios_xe = 16.12.3s`\n- `ios_xe = 16.12.4`\n- `ios_xe = 16.12.4a`\n- `ios_xe = 16.12.5`\n- `ios_xe = 16.12.5a`\n- `ios_xe = 16.12.5b`\n- `ios_xe = 16.12.6`\n- `ios_xe = 16.12.6a`\n- `ios_xe = 16.12.7`\n- `ios_xe = 16.12.8`\n- `ios_xe = 16.12.9`\n- `ios_xe = 16.12.10`\n- `ios_xe = 16.12.10a`\n- `ios_xe = 16.12.11`\n- `ios_xe = 16.12.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **cisco-sa-hardening-iosxe-V8NMuMZJ** · Cisco · affected: Cisco IOS XE Software (595 versions) · updated 2026-08-05 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxe-V8NMuMZJ)","depth":"twilight","depthScore":47,"depthScoreParts":{"impact":47.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}