← Vulnerability feed

Vulnerability record · CVE-2021-1565 · published 23 September 2021

CVE-2021-1565: Cisco ios xe double free vulnerability

Cisco · Ios Xe

Multiple vulnerabilities in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. These vulnerabilities are due to insufficient validation of CAPWAP packets. An attacker could exploit the vulnerabilities by sending a malformed CAPWAP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition.

8.6 CVSS 3.1 High EPSS 1.3% · top 30.8% CWE-415 · Double free
8.6CVSS 3.1 base score, v2 5.0
1.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

Multiple vulnerabilities in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. These vulnerabilities are due to insufficient validation of CAPWAP packets. An attacker could exploit the vulnerabilities by sending a malformed CAPWAP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-capwap-dos-gmNjdKOY Vendor Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-capwap-dos-gmNjdKOY Vendor Advisory

Track CVE-2021-1565 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2023-20198Cisco IOS XE Web UI unauthenticated privilege escalation and implant deploymentCVE-2023-20198 is a critical flaw in the Cisco IOS XE web UI that lets an unauthenticated remote attacker gain initial access and create a local priv…KEVEPSS 100%analysed9.8CVE-2018-0151Cisco IOS/IOS XE QoS UDP Port 18999 Buffer OverflowCisco IOS and IOS XE contain a buffer overflow in the QoS subsystem caused by incorrect bounds checking of values in packets sent to UDP port 18999. …KEVEPSS 14%analysed9.8CVE-2017-3881Cisco IOS/IOS XE CMP Telnet Option Handling RCECisco IOS and IOS XE fail to restrict CMP-specific Telnet options to internal cluster communications and mishandle malformed CMP Telnet options, so a…KEVEPSS 99%analysed8.8CVE-2018-0167Cisco IOS, IOS XE and IOS XR LLDP buffer overflowMultiple buffer overflow flaws exist in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS, IOS XE and IOS XR Software. An unauthenticat…KEVEPSS 3.4%analysed8.8CVE-2017-6740Cisco IOS and IOS XE SNMP buffer overflow allows remote code executionCisco IOS and IOS XE contain a buffer overflow in the SNMP subsystem affecting SNMP versions 1, 2c, and 3. An authenticated remote attacker can send …KEVEPSS 11%analysed8.8CVE-2017-6738Cisco IOS and IOS XE SNMP buffer overflow allows remote code executionThe SNMP subsystem in Cisco IOS and IOS XE Software contains a buffer overflow that affects SNMP versions 1, 2c, and 3. An authenticated remote attac…KEVEPSS 11%analysed8.8CVE-2017-6743Cisco IOS and IOS XE SNMP buffer overflow allows remote code executionThe SNMP subsystem in Cisco IOS and IOS XE Software contains a buffer overflow that an authenticated, remote attacker can trigger with a crafted SNMP…KEVEPSS 11%analysed8.8CVE-2017-6736Cisco IOS and IOS XE SNMP buffer overflow remote code executionThe SNMP subsystem in Cisco IOS and IOS XE contains a buffer overflow that can be triggered by a crafted SNMP packet sent over IPv4 or IPv6. It affec…KEVEPSS 70%analysed

Source: NIST National Vulnerability Database (record CVE-2021-1565), CISA KEV, FIRST EPSS (scores of 2026-10-05). This page is refreshed as NVD updates the record.