EUVD-2026-53457
GHSA-g2mx-jm98-x82v
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
IOS XE processes unauthenticated network traffic; scope change reflects full device reload impacting all services; no confidentiality or integrity impact is supported by the description.
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-2026-20271 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-691.
AnalysisAI
Unauthenticated remote denial-of-service in Cisco IOS XE Software allows network-accessible attackers to crash IOS processes or force full device reloads by exploiting insufficient control flow management flaws (CWE-691), with a scope-changing availability impact rated CVSS 8.6. The vulnerabilities were discovered internally by Cisco's own engineering team as part of a proactive security review and addressed through software hardening releases - no active exploitation or public proof-of-concept has been identified at time of analysis. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | No special configuration or authentication is required based on the CVSS vector (AV:N/AC:L/PR:N/UI:N): exploitation is possible by unauthenticated remote attackers against any network-reachable Cisco IOS XE device running an affected version without the need for an established session, authenticated access, or any non-default configuration state. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 8.6 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H) represents a high-severity, low-friction network denial-of-service: no authentication, no user interaction, low complexity, and scope-changing availability loss. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An unauthenticated attacker on any network path to a vulnerable Cisco IOS XE device - such as an ISP customer sending crafted packets toward an enterprise edge router - sends a specially constructed packet or packet sequence that triggers a control flow management defect in the IOS XE software stack. The defective code path causes a critical IOS process to fault, leading to a full device reload and a network outage affecting all traffic transiting or terminating at the device for the duration of recovery. … |
| Remediation | The primary remediation is upgrading to a Cisco-released fixed version of IOS XE Software as specified in the Software Fixed Releases table within the Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-iosxe-V8NMuMZJ - specific fixed version numbers are not present in the available intelligence data and must be confirmed directly from that advisory before planning upgrades. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, conduct a complete asset inventory of all Cisco IOS XE devices and document installed versions, prioritizing production and critical infrastructure segments. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
More in Cisco Ios Xe Software
View allImproper neutralization of special elements (CWE-74 injection class) in Cisco IOS XE Software allows remote, unauthentic
Authentication bypass and improper access control in Cisco IOS XE Software allow a remote, unauthenticated attacker to g
Denial-of-service via malformed XMCP packets forces unexpected reloads of Cisco IOS and IOS XE devices, exploitable by a
Denial-of-service in Cisco IOS XE Software's Blocks Extensible Exchange Protocol (BEEP) feature allows an unauthenticate
Unauthenticated remote denial-of-service affecting Cisco IOS XE Software across a wide version range results from multip
Denial-of-service conditions in Cisco IOS XE Software stem from multiple incorrect calculation flaws (CWE-682) discovera
Unauthenticated remote attackers can cause high availability impact with scope change on Cisco IOS XE Software through i
Remote unauthenticated exploitation of improper memory buffer boundary handling in Cisco IOS XE Software can cause a com
Denial of service in Cisco IOS XE Software's SNMP subsystem allows an authenticated remote attacker to force an affected
Denial of service in Cisco IOS XE Software's web-based management interface allows an authenticated remote attacker with
Denial-of-service in Cisco IOS XE Software's web-based management interface (WebUI) allows an authenticated remote attac
Same weakness CWE-691 – Insufficient Control Flow Management
View allSame technique Information Disclosure
View allShare
External POC / Exploit Code
Leaving vuln.today