iOS vulnerabilities

67 known vulnerabilities in iOS from Cisco. 58 are rated high or critical, and 39 have been exploited in real attacks. Each entry lists the affected versions and the release that fixes it, where the vendor has published one.

Latest first

• 8.6 High severity

  Cisco IOS XE Software: Unchecked Input for Loop Condition

  CVE-2026-20301Aug 5, 2026Cisco

  A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition o

• 7.7 High severity

  IOS: Improper Handling of Syntactically Invalid Structure

  CVE-2026-20125Mar 25, 2026Cisco

  A vulnerability in the HTTP Server feature of Cisco IOS Software and Cisco IOS XE Software Release 3E could allow an authenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulne

• 8.6 High severity

  IOS: Missing Release of Memory after Effective Lifetime

  CVE-2026-20012Mar 25, 2026Cisco

  A vulnerability in the Internet Key Exchange version 2 (IKEv2) feature of Cisco IOS Software, Cisco IOS XE Software, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauth

• 9.0 Critical severity

  IOS: Heap-based Buffer Overflow

  CVE-2025-20363Sep 25, 2025CiscoEPSS 7.16%

  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, r

• 7.7 High severity

  Cisco IOS and IOS XE Software SNMP Denial of Service and Remote Code Execution Exploited

  CVE-2025-20352Sep 24, 2025CiscoEPSS 40.6%

  A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow the following: An authenticated, remote attacker with low privileges could cause a denial of service (DoS) condition on an af

• 7.7 High severity

  IOS: Improper Validation of Specified Type of Input

  CVE-2025-20327Sep 24, 2025Cisco

  A vulnerability in the web UI of Cisco IOS Software could allow an authenticated, remote attacker with low privileges to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper input validation. An attacker could

• 8.1 High severity

  IOS: Improper Authentication

  CVE-2025-20160Sep 24, 2025Cisco

  A vulnerability in the implementation of the TACACS+ protocol in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to view sensitive data or bypass authentication. This vulnerability exists because the system does not

• 8.6 High severity

  IOS: Missing Release of Memory after Effective Lifetime

  CVE-2025-20239Aug 14, 2025Cisco

  A vulnerability in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, Secure Firewall Adaptive Security Appliance (ASA) Software, and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote

• 8.3 High severity

  IOS: Missing Authorization

  CVE-2025-20164May 7, 2025Cisco

  A vulnerability in the Cisco Industrial Ethernet Switch Device Manager (DM) of Cisco IOS Software could allow an authenticated, remote attacker to elevate privileges. This vulnerability is due to insufficient validation of authorizations for authenticated user

• 8.6 High severity

  A vulnerability in the Two-Way Active Measurement Protocol (TWAMP) server feature of Cisco IOS…

  CVE-2025-20154May 7, 2025Cisco

  A vulnerability in the Two-Way Active Measurement Protocol (TWAMP) server feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) con

• 7.7 High severity

  IOS: Uncaught Exception

  CVE-2025-20176Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Buffer Access with Incorrect Length Value

  CVE-2025-20175Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Buffer Access with Incorrect Length Value

  CVE-2025-20174Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Uncaught Exception

  CVE-2025-20173Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Uncaught Exception

  CVE-2025-20172Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling whe

• 7.7 High severity

  IOS: Uncaught Exception

  CVE-2025-20171Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Buffer Access with Incorrect Length Value

  CVE-2025-20170Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.7 High severity

  IOS: Buffer Access with Incorrect Length Value

  CVE-2025-20169Feb 5, 2025Cisco

  A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests.

• 7.5 High severity

  IOS: Out-of-bounds Write

  CVE-2024-20433Sep 25, 2024Cisco

  A vulnerability in the Resource Reservation Protocol (RSVP) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condi

• 7.5 High severity

  IOS: Out-of-bounds Write

  CVE-2024-20308Mar 27, 2024Cisco

  A vulnerability in the IKEv1 fragmentation code of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a heap underflow, resulting in an affected device reloading. This vulnerability exists because crafted, fra

• 7.5 High severity

  IOS: Stack-based Buffer Overflow

  CVE-2024-20307Mar 27, 2024Cisco

  A vulnerability in the IKEv1 fragmentation code of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a heap overflow, resulting in an affected device reloading. This vulnerability exists because crafted, frag

• 7.4 High severity

  IOS: NULL Pointer Dereference

  CVE-2024-20312Mar 27, 2024Cisco

  A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulner

• 7.5 High severity

  IOS: Uncontrolled Recursion

  CVE-2024-20311Mar 27, 2024Cisco

  A vulnerability in the Locator ID Separation Protocol (LISP) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability is due to the incorrect handling of L

• 7.4 High severity

  IOS: Uncaught Exception

  CVE-2024-20276Mar 27, 2024Cisco

  A vulnerability in Cisco IOS Software for Cisco Catalyst 6000 Series Switches could allow an unauthenticated, adjacent attacker to cause an affected device to reload unexpectedly. This vulnerability is due to improper handling of process-switched traffic. An a

• 9.1 Critical severity

  IOS: Improper Authorization

  CVE-2023-20186Sep 27, 2023Cisco

  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 aff

• 6.6 Medium severity

  Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Exploited

  CVE-2023-20109Sep 27, 2023CiscoEPSS 2.5%

  A vulnerability in the Cisco Group Encrypted Transport VPN (GET VPN) feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker who has administrative control of either a group member or a key server to execute arbitr

• 7.5 High severity

  Cisco IOS: Improper Validation of Array Index

  CVE-2023-20080Mar 23, 2023Cisco

  A vulnerability in the IPv6 DHCP version 6 (DHCPv6) relay and server features of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition. This vulnerability is due to insufficient validation

• 7.7 High severity

  Cisco IOS: Improper Handling of Exceptional Conditions

  CVE-2022-20920Oct 10, 2022Cisco

  A vulnerability in the SSH implementation of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload. This vulnerability is due to improper handling of resources during an exceptional sit

• 7.5 High severity

  Cisco IOS: Improper Handling of Exceptional Conditions

  CVE-2022-20726Apr 15, 2022CiscoEPSS 1.13%

  Multiple vulnerabilities in the Cisco IOx application hosting environment on multiple Cisco platforms could allow an attacker to inject arbitrary commands into the underlying host operating system, execute arbitrary code on the underlying host operating system

• 8.6 High severity

  Cisco IOS: Missing Release of Resource after Effective Lifetime

  CVE-2022-20697Apr 15, 2022CiscoEPSS 1.16%

  A vulnerability in the web services interface of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper resource management in the HTTP serv

• 5.9 Medium severity

  Cisco IOS Software Denial-of-Service Exploited

  CVE-2018-0180Mar 28, 2018Cisco IOSEPSS 4.93%

  Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a reload of an affected system, resulting in a denial of service (DoS) condition. These vulnerabilities af

• 5.9 Medium severity

  Cisco IOS Software Denial-of-Service Exploited

  CVE-2018-0179Mar 28, 2018Cisco IOSEPSS 4.93%

  Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a reload of an affected system, resulting in a denial of service (DoS) condition. These vulnerabilities af

• 8.0 High severity

  Cisco IOS, XR, and XE Software Buffer Overflow Exploited

  CVE-2018-0175Mar 28, 2018Cisco IOS, IOS XE, and IOS XREPSS 3.48%

  Format String vulnerability in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition or execute

• 8.6 High severity

  Cisco IOS Software and Cisco IOS XE Software Improper Input Validation Exploited

  CVE-2018-0174Mar 28, 2018Cisco IOS and IOS XEEPSS 7.61%

  A vulnerability in the DHCP option 82 encapsulation functionality of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulne

• 8.6 High severity

  Cisco IOS and IOS XE Software Improper Input Validation Exploited

  CVE-2018-0173Mar 28, 2018Cisco IOS and IOS XEEPSS 7.61%

  A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in

• 8.6 High severity

  Cisco IOS and IOS XE Software Improper Input Validation Exploited

  CVE-2018-0172Mar 28, 2018Cisco IOS and IOS XEEPSS 7.82%

  A vulnerability in the DHCP option 82 encapsulation functionality of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulne

• 9.8 Critical severity

  Cisco IOS and IOS XE Software Smart Install Remote Code Execution Exploited

  CVE-2018-0171Mar 28, 2018Cisco IOS and IOS XEEPSS 99.5%

  A vulnerability in the Smart Install feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition, or to execute arbitrary co

• 8.8 High severity

  Cisco IOS, XR, and XE Software Buffer Overflow Exploited

  CVE-2018-0167Mar 28, 2018Cisco IOS, IOS XE, and IOS XREPSS 3.35%

  Multiple Buffer Overflow vulnerabilities in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) conditio

• 6.3 Medium severity

  Cisco IOS Software Resource Management Errors Exploited

  CVE-2018-0161Mar 28, 2018Cisco IOSEPSS 4.12%

  A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software running on certain models of Cisco Catalyst Switches could allow an authenticated, remote attacker to cause a denial of service (DoS) condition, aka a GET MIB Obje

• 7.5 High severity

  Cisco IOS and XE Software Internet Key Exchange Version 1 Denial-of-Service Exploited

  CVE-2018-0159Mar 28, 2018Cisco IOS and IOS XEEPSS 6.87%

  A vulnerability in the implementation of Internet Key Exchange Version 1 (IKEv1) functionality in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of servi