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Cisco IOS XE CVE-2026-20263

| EUVDEUVD-2026-53452 HIGH
7PK - Errors (CWE-388)
2026-08-05 cisco GHSA-wrfp-gcwf-q2vv
8.6
CVSS 3.1 · Vendor: cisco
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Severity by source

Vendor (cisco) PRIMARY
8.6 HIGH
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
vuln.today AI
8.6 HIGH

Network-accessible unauthenticated parse flaw with no special conditions; Changed scope reflects device reload cascading availability loss to all downstream network-dependent systems.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Aug 05, 2026 - 17:30 vuln.today
CVE Published
Aug 05, 2026 - 16:18 nvd
HIGH 8.6

DescriptionCVE.org

A vulnerability in the Blocks Extensible Exchange Protocol (BEEP) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to improper handling when parsing a specific BEEP SOAP request. An attacker could exploit this vulnerability by sending a specific BEEP SOAP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.

AnalysisAI

Denial-of-service in Cisco IOS XE Software's Blocks Extensible Exchange Protocol (BEEP) feature allows an unauthenticated remote attacker to force an unexpected device reload by sending a specially crafted BEEP SOAP request. The CVSS 8.6 score with Changed scope (S:C) reflects that a device reload disrupts all network services downstream of the affected device, amplifying impact beyond the immediate target. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Identify IOS XE device with BEEP enabled and reachable
Delivery
Craft malformed BEEP SOAP request
Exploit
Send request to BEEP listener (no auth required)
Execution
Trigger CWE-388 parse error in BEEP handler
Persist
IOS XE process crashes, device reloads
Impact
Network DoS disrupts downstream hosts and services

Vulnerability AssessmentAI

Exploitation The BEEP (Blocks Extensible Exchange Protocol) feature must be explicitly configured and enabled on the Cisco IOS XE device - BEEP is not a default-enabled service in standard IOS XE deployments, limiting the exposed population to devices where an administrator has deliberately configured BEEP functionality. … 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) presents a high real-world risk signal: the attack requires no authentication, no user interaction, and low complexity, and is exploitable over the network. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker with network access to a Cisco IOS XE device - whether via direct internet exposure, VPN, or internal lateral movement - identifies a device with the BEEP feature enabled and sends a single specially crafted BEEP SOAP request to the BEEP listener port. The malformed request triggers the CWE-388 error-handling failure in the BEEP parser, causing the IOS XE process to crash and the device to reload unexpectedly, dropping all active sessions and disrupting routing or switching for the duration of the reload cycle. …
Remediation The primary remediation is to upgrade to a fixed Cisco IOS XE Software release as specified in the Cisco Security Advisory cisco-sa-iosxe-bing-MGHrFAkd (https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-bing-MGHrFAkd). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours: Inventory all Cisco IOS XE devices with BEEP enabled and determine internet/network exposure; disable BEEP via configuration where operationally feasible. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-20263 vulnerability details – vuln.today

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