EUVD-2026-53455
GHSA-mjcr-83m5-gm8c
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
IOS XE processes network protocol traffic without authentication at AV:N; resource exhaustion propagates to adjacent control-plane components justifying S:C; no confidentiality or integrity impact is supported by available evidence.
Primary rating from Vendor (cisco).
CVSS VectorVendor: cisco
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Lifecycle Timeline
2DescriptionCVE.org
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 vulnerabilities tracked by CVE-2026-20269 are related to issues with improper control of a resource through its lifetime that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-664.
AnalysisAI
Unauthenticated remote attackers can cause high availability impact with scope change on Cisco IOS XE Software through improper control of resources across their lifetime (CWE-664), affecting an exceptionally broad version range from 16.6.x through 26.1.x. The vulnerabilities were discovered proactively by Cisco's internal security engineering team and grouped as a software hardening release, meaning patches were prepared before external threat actor awareness. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The CVSS vector (AV:N/AC:L/PR:N/UI:N) indicates no authentication, no elevated privileges, no user interaction, and low attack complexity are required to exploit this vulnerability against a network-accessible IOS XE device. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The official CVSS 8.6 score (AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H) places this at high priority for network operations teams: no authentication required, low attack complexity, no user interaction, and a scope change indicating potential cascading availability impact across adjacent components. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An unauthenticated attacker on the network sends crafted protocol traffic to an exposed Cisco IOS XE device, exercising a code path where an internal resource (such as a memory buffer, process socket, or state table entry) is allocated but never properly released. Under sustained or repeated triggering, the resource pool is exhausted, causing the relevant IOS XE process to crash or the device to reload - interrupting routing, switching, or WAN aggregation functions for all dependent network segments. … |
| Remediation | The primary remediation is to upgrade to a Cisco-recommended fixed release as specified in the Cisco Security Advisory cisco-sa-hardening-iosxe-V8NMuMZJ, available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxe-V8NMuMZJ; exact fixed version numbers per release train are not confirmed in the available data and must be determined via Cisco's Software Checker tool within that advisory. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Complete an inventory of all Cisco IOS XE devices in production, document their current software versions against the affected range (16.6.x through 26.1.x), and contact Cisco TAC for patch release timeline confirmation. …
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