A vulnerability in the Out-of-Band Access Point (AP) Image Download, the Clean Air Spectral Recording, and the client debug bundles features of Cisco IOS XE Software for Wireless LAN Controllers (WLCs) could allow an unauthenticated, remote attacker to upload arbitrary files to an affected system. This vulnerability is due to the presence of a hard-coded JSON Web Token (JWT) on an affected system. An attacker could exploit this vulnerability by sending crafted HTTPS requests to the AP file upload interface. A successful exploit could allow the attacker to upload files, perform path traversal, and execute arbitrary commands with root privileges.

Cisco IOS XE Web UI contains a privilege escalation vulnerability in the web user interface that could allow a remote, unauthenticated attacker to create an account with privilege level 15 access. The attacker can then use that account to gain control of the affected device.

A vulnerability in the Transaction Language 1 (TL1) code of Cisco ASR 900 Series routers could allow an unauthenticated, remote attacker to cause a reload of, or remotely execute code on, the affected system. This vulnerability affects Cisco ASR 900 Series Aggregation Services Routers (ASR902, ASR903, and ASR907) that are running the following releases of Cisco IOS XE Software: 3.17.0S 3.17.1S 3.17.2S 3.18.0S 3.18.1S. More Information: CSCuy15175. Known Affected Releases: 15.6(1)S 15.6(2)S. Known Fixed Releases: 15.6(1)S2.12 15.6(1.17)S0.41 15.6(1.17)SP 15.6(2)SP 16.4(0.183) 16.5(0.10).

A vulnerability in the REST API of the web-based user interface (web UI) of Cisco IOS XE 3.1 through 16.5 could allow an unauthenticated, remote attacker to bypass authentication to the REST API of the web UI of the affected software. The vulnerability is due to insufficient input validation for the REST API of the affected software. An attacker could exploit this vulnerability by sending a malicious API request to an affected device. A successful exploit could allow the attacker to bypass authentication and gain access to the web UI of the affected software. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS XE Software, if the HTTP Server feature is enabled for the device. The newly redesigned, web-based administration UI was introduced in the Denali 16.2 Release of Cisco IOS XE Software. This vulnerability does not affect the web-based administration UI in earlier releases of Cisco IOS XE Software. Cisco Bug IDs: CSCuz46036.

A vulnerability 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 execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a logic error that occurs during the validation of CAPWAP packets. An attacker could exploit this vulnerability by sending a crafted CAPWAP packet to an affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the affected device to crash and reload, resulting in a DoS condition.

A vulnerability in the authorization controls for the Cisco IOx application hosting infrastructure in Cisco IOS XE Software could allow an unauthenticated, remote attacker to execute Cisco IOx API commands without proper authorization. The vulnerability is due to incorrect handling of requests for authorization tokens. An attacker could exploit this vulnerability by using a crafted API call to request such a token. An exploit could allow the attacker to obtain an authorization token and execute any of the IOx API commands on an affected device.

A vulnerability in the Cisco REST API virtual service container for Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass authentication on the managed Cisco IOS XE device. The vulnerability is due to an improper check performed by the area of code that manages the REST API authentication service. An attacker could exploit this vulnerability by submitting malicious HTTP requests to the targeted device. A successful exploit could allow the attacker to obtain the token-id of an authenticated user. This token-id could be used to bypass authentication and execute privileged actions through the interface of the REST API virtual service container on the affected Cisco IOS XE device. The REST API interface is not enabled by default and must be installed and activated separately on IOS XE devices. See the Details section for more information.

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-2026-20272 are related to issues with improper neutralization of special elements that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-74.

A vulnerability in the quality of service (QoS) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or execute arbitrary code with elevated privileges. The vulnerability is due to incorrect bounds checking of certain values in packets that are destined for UDP port 18999 of an affected device. An attacker could exploit this vulnerability by sending malicious packets to an affected device. When the packets are processed, an exploitable buffer overflow condition may occur. A successful exploit could allow the attacker to execute arbitrary code on the affected device with elevated privileges. The attacker could also leverage this vulnerability to cause the device to reload, causing a temporary DoS condition while the device is reloading. The malicious packets must be destined to and processed by an affected device. Traffic transiting a device will not trigger the vulnerability. Cisco Bug IDs: CSCvf73881.

A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges. The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors: (1) the failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device; and (2) the incorrect processing of malformed CMP-specific Telnet options. An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device. This affects Catalyst switches, Embedded Service 2020 switches, Enhanced Layer 2 EtherSwitch Service Module, Enhanced Layer 2/3 EtherSwitch Service Module, Gigabit Ethernet Switch Module (CGESM) for HP, IE Industrial Ethernet switches, ME 4924-10GE switch, RF Gateway 10, and SM-X Layer 2/3 EtherSwitch Service Module. Cisco Bug IDs: CSCvd48893.

A vulnerability in the authentication, authorization, and accounting (AAA) function of Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass NETCONF or RESTCONF authentication and do either of the following: Install, manipulate, or delete the configuration of an affected device Cause memory corruption that results in a denial of service (DoS) on an affected device This vulnerability is due to an uninitialized variable. An attacker could exploit this vulnerability by sending a series of NETCONF or RESTCONF requests to an affected device. A successful exploit could allow the attacker to use NETCONF or RESTCONF to install, manipulate, or delete the configuration of a network device or to corrupt memory on the device, resulting a DoS.

A vulnerability in the implementation of the Locator/ID Separation Protocol (LISP) in Cisco IOS XE 3.2 through 16.5 could allow an unauthenticated, remote attacker using an x tunnel router to bypass authentication checks performed when registering an Endpoint Identifier (EID) to a Routing Locator (RLOC) in the map server/map resolver (MS/MR). The vulnerability is due to a logic error introduced via a code regression for the affected software. An attacker could exploit this vulnerability by sending specific valid map-registration requests, which will be accepted by the MS/MR even if the authentication keys do not match, to the affected software. A successful exploit could allow the attacker to inject invalid mappings of EIDs to RLOCs in the MS/MR of the affected software. This vulnerability affects Cisco devices that are configured with LISP acting as an IPv4 or IPv6 map server. This vulnerability affects Cisco IOS XE Software release trains 3.9E and Everest 16.4. Cisco Bug IDs: CSCvc18008.

A vulnerability in the Easy Virtual Switching System (VSS) feature of Cisco IOS XE Software for Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches could allow an unauthenticated, remote attacker to execute arbitrary code on the underlying Linux operating system of an affected device. The vulnerability is due to incorrect boundary checks of certain values in Easy VSS protocol packets that are destined for an affected device. An attacker could exploit this vulnerability by sending crafted Easy VSS protocol packets to UDP port 5500 while the affected device is in a specific state. When the crafted packet is processed, a buffer overflow condition may occur. A successful exploit could allow the attacker to trigger a denial of service (DoS) condition or execute arbitrary code with root privileges on the underlying Linux operating system of the affected device.

A vulnerability in the authentication, authorization, and accounting (AAA) security services of Cisco IOS XE Software could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device or cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to incorrect memory operations that the affected software performs when the software parses a username during login authentication. An attacker could exploit this vulnerability by attempting to authenticate to an affected device. A successful exploit could allow the attacker to execute arbitrary code on the affected device or cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are running Cisco IOS XE Software Release Fuji 16.7.1 or Fuji 16.8.1 and are configured to use AAA for login authentication. Cisco Bug IDs: CSCvi25380.

This advisory is part of the March 28, 2018, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 20 Cisco Security Advisories that describe 22 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

This advisory is part of the March 28, 2018, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 20 Cisco Security Advisories that describe 22 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

A vulnerability in the Central Web Authentication (CWA) feature of Cisco IOS XE Software for Wireless Controllers could allow an unauthenticated, adjacent attacker to bypass the pre-authentication access control list (ACL), which could allow access to network resources before user authentication. This vulnerability is due to a logic error when activating the pre-authentication ACL that is received from the authentication, authorization, and accounting (AAA) server. An attacker could exploit this vulnerability by connecting to a wireless network that is configured for CWA and sending traffic through an affected device that should be denied by the configured ACL before user authentication. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device before the user authentication is completed, allowing the attacker to access trusted networks that the device might be protecting.

The SSHv2 functionality in Cisco IOS 15.2, 15.3, 15.4, and 15.5 and IOS XE 3.6E before 3.6.3E, 3.7E before 3.7.1E, 3.10S before 3.10.6S, 3.11S before 3.11.4S, 3.12S before 3.12.3S, 3.13S before 3.13.3S, and 3.14S before 3.14.1S does not properly implement RSA authentication, which allows remote attackers to obtain login access by leveraging knowledge of a username and the associated public key, aka Bug ID CSCus73013.

A vulnerability in the vDaemon process in Cisco IOS XE SD-WAN Software could allow an unauthenticated, remote attacker to cause a buffer overflow on an affected device. This vulnerability is due to insufficient bounds checking when the device processes traffic. An attacker could exploit this vulnerability by sending crafted traffic to the device. The attacker must have a man-in-the-middle position between Cisco vManage and an associated device that is running an affected version of Cisco IOS XE SD-WAN Software. An exploit could allow the attacker to conduct a controllable buffer overflow attack (and possibly execute arbitrary commands as the root user) or cause a device reload, resulting in a denial of service (DoS) condition.

A vulnerability in the Authentication, Authorization, and Accounting (AAA) feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to bypass command authorization and copy files to or from the file system of an affected device using the Secure Copy Protocol (SCP). This vulnerability is due to incorrect processing of SCP commands in AAA command authorization checks. An attacker with valid credentials and level 15 privileges could exploit this vulnerability by using SCP to connect to an affected device from an external machine. A successful exploit could allow the attacker to obtain or change the configuration of the affected device and put files on or retrieve files from the affected device.

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which may lead to the complete compromise of the affected device. For more information about this vulnerability, see the Details ["#details"] section of this advisory.

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-2026-20267 are related to improper access control issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-284.

Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE Software. We are updating the list of fixed releases and adding the Software Checker.Fix information can be found in the Fixed Software section

Cisco IOS XE contains a command injection vulnerability in the web user interface that could allow a remote, authenticated attacker to inject commands that can be executed as the root user.

A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit this vulnerability by sending a crafted SNMP packet to the affected device.  The vulnerability is due to a buffer overflow in the affected code area. The vulnerability affects all versions of SNMP (versions 1, 2c, and 3). The attacker must know the SNMP read only community string (SNMP version 2c or earlier) or the user credentials (SNMPv3). An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or to cause a reload of the affected system. Only traffic directed to the affected system can be used to exploit this vulnerability.

The Autonomic Networking Infrastructure (ANI) implementation in Cisco IOS 12.2, 12.4, 15.0, 15.2, 15.3, and 15.4 and IOS XE 3.10.xS through 3.13.xS before 3.13.1S allows remote attackers to spoof Autonomic Networking Registration Authority (ANRA) responses, and consequently bypass intended device and node access restrictions or cause a denial of service (disrupted domain access), via crafted AN messages, aka Bug ID CSCup62191.

A vulnerability in the web-based user interface (Web UI) of Cisco IOS XE Software could allow an authenticated, remote attacker to execute commands on the underlying Linux shell of an affected device with root privileges. The vulnerability occurs because the affected software improperly sanitizes user-supplied input. An attacker who has valid administrator access to an affected device could exploit this vulnerability by supplying a crafted input parameter on a form in the Web UI and then submitting that form. A successful exploit could allow the attacker to run arbitrary commands on the device with root privileges, which may lead to complete system compromise.

A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated but unprivileged (level 1), remote attacker to run privileged Cisco IOS commands by using the web UI. The vulnerability is due to a failure to validate and sanitize input in Web Services Management Agent (WSMA) functions. An attacker could exploit this vulnerability by submitting a malicious payload to the affected device's web UI. A successful exploit could allow the lower-privileged attacker to execute arbitrary commands with higher privileges on the affected device.

A vulnerability in the web-based Wireless Controller GUI of Cisco IOS XE Software for Cisco 5760 Wireless LAN Controllers, Cisco Catalyst 4500E Supervisor Engine 8-E (Wireless) Switches, and Cisco New Generation Wireless Controllers (NGWC) 3850 could allow an authenticated, remote attacker to elevate their privileges on an affected device. The vulnerability is due to incomplete input validation of HTTP requests by the affected GUI, if the GUI connection state or protocol changes. An attacker could exploit this vulnerability by authenticating to the Wireless Controller GUI as a Lobby Administrator user of an affected device and subsequently changing the state or protocol for their connection to the GUI. A successful exploit could allow the attacker to elevate their privilege level to administrator and gain full control of the affected device. This vulnerability affects the following Cisco products if they are running Cisco IOS XE Software Release 3.7.0E, 3.7.1E, 3.7.2E, 3.7.3E, 3.7.4E, or 3.7.5E: Cisco 5760 Wireless LAN Controllers, Cisco Catalyst 4500E Supervisor Engine 8-E (Wireless) Switches, Cisco New Generation Wireless Controllers (NGWC) 3850. Cisco Bug IDs: CSCvd73746.

A vulnerability in the web-based user interface (web UI) of Cisco IOS XE 16.2 could allow an authenticated, remote attacker to elevate their privileges on an affected device. The vulnerability is due to incorrect default permission settings for new users who are created by using the web UI of the affected software. An attacker could exploit this vulnerability by using the web UI of the affected software to create a new user and then logging into the web UI as the newly created user. A successful exploit could allow the attacker to elevate their privileges on the affected device. This vulnerability affects Cisco devices that are running a vulnerable release Cisco IOS XE Software, if the HTTP Server feature is enabled for the device. The newly redesigned, web-based administration UI was introduced in the Denali 16.2 Release of Cisco IOS XE Software. This vulnerability does not affect the web-based administration UI in earlier releases of Cisco IOS XE Software. Cisco Bug IDs: CSCuy83062.