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Cisco IOS

Ranked by severity, then by exploit likelihood. Click a CVE ID for its full record.

620CVEs
CVE-2022-20697
Cisco IOS and IOS XE Software Web Services Denial of Service Vulnerability
Published 2022-04-15 · Modified
8.6EPSS 0.012
CVE-2023-20080
Cisco IOS and IOS XE Software IPv6 DHCP (DHCPv6) Relay and Server Denial of Service Vulnerability
Published 2023-03-23 · Modified
8.6EPSS 0.010
CVE-2024-20311
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 LISP packets. An attacker could exploit this vulnerability by sending a crafted LISP packet to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition. Note: This vulnerability could be exploited over either IPv4 or IPv6 transport.
Published 2024-03-27 · Analyzed
8.6EPSS 0.008
CVE-2024-20308
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, fragmented IKEv1 packets are not properly reassembled. An attacker could exploit this vulnerability by sending crafted UDP packets to an affected system. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. Note: Only traffic that is directed to the affected system can be used to exploit this vulnerability. This vulnerability can be triggered by IPv4 and IPv6 traffic..
Published 2024-03-27 · Analyzed
8.6EPSS 0.008
CVE-2024-20433
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) condition. This vulnerability is due to a buffer overflow when processing crafted RSVP packets. An attacker could exploit this vulnerability by sending RSVP traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
Published 2024-09-25 · Analyzed
8.6EPSS 0.006
CVE-2026-20301
Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol Denial of Service Vulnerability
Published 2026-08-05 · Analyzed
8.6EPSS 0.006
CVE-2025-20154
Cisco IOS, IOS XE and IOS XR Software TWAMP Denial of Service Vulnerability
Published 2025-05-07 · Analyzed
8.6EPSS 0.005
CVE-2026-20012
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 unauthenticated, remote attacker to trigger a memory leak, resulting in a denial of service (DoS) condition on an affected device. This vulnerability is due to improper parsing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit of Cisco IOS Software and IOS XE Software could allow the attacker to cause the affected device to reload, resulting in a DoS condition. A successful exploit of Cisco Secure Firewall ASA Software and Secure FTD Software could allow the attacker to partially exhaust system memory, resulting in system instability, such as the inability to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition.
Published 2026-03-25 · Analyzed
8.6EPSS 0.004
CVE-2012-0384
Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x and 3.1.xS before 3.1.2S, 3.2.xS through 3.4.xS before 3.4.2S, 3.5.xS before 3.5.1S, and 3.1.xSG and 3.2.xSG before 3.2.2SG, when AAA authorization is enabled, allow remote authenticated users to bypass intended access restrictions and execute commands via a (1) HTTP or (2) HTTPS session, aka Bug ID CSCtr91106.
Published 2012-03-29 · Modified
8.5EPSS 0.039
CVE-2008-3805
Cisco IOS 12.0 through 12.4 on Cisco 10000, uBR10012 and uBR7200 series devices handles external UDP packets that are sent to 127.0.0.0/8 addresses intended for IPC communication within the device, which allows remote attackers to cause a denial of service (device or linecard reload) via crafted UDP packets, a different vulnerability than CVE-2008-3806.
Published 2008-09-26 · Modified
8.5EPSS 0.033
CVE-2008-3806
Cisco IOS 12.0 through 12.4 on Cisco 10000, uBR10012 and uBR7200 series devices handles external UDP packets that are sent to 127.0.0.0/8 addresses intended for IPC communication within the device, which allows remote attackers to cause a denial of service (device or linecard reload) via crafted UDP packets, a different vulnerability than CVE-2008-3805.
Published 2008-09-26 · Modified
8.5EPSS 0.031
CVE-2007-4263
Unspecified vulnerability in the server side of the Secure Copy (SCP) implementation in Cisco 12.2-based IOS allows remote authenticated users to read, write or overwrite any file on the device's filesystem via unknown vectors.
Published 2007-08-08 · Modified
8.5EPSS 0.026
CVE-2016-6380
The DNS forwarder in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.15 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (data corruption or device reload) via a crafted DNS response, aka Bug ID CSCup90532.
Published 2016-10-05 · Modified
8.3EPSS 0.030
CVE-2020-3475
Cisco IOS XE Software Web Management Framework Vulnerabilities
Published 2020-09-24 · Modified
8.1EPSS 0.014
CVE-2020-3257
Cisco IOx Application Environment for IOS Software for Cisco Industrial Routers Vulnerabilities
Published 2020-06-03 · Modified
8.1EPSS 0.007
CVE-2025-20160
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 properly check whether the required TACACS+ shared secret is configured. A machine-in-the-middle attacker could exploit this vulnerability by intercepting and reading unencrypted TACACS+ messages or impersonating the TACACS+ server and falsely accepting arbitrary authentication requests. A successful exploit could allow the attacker to view sensitive information in a TACACS+ message or bypass authentication and gain access to the affected device.
Published 2025-09-24 · Analyzed
8.1EPSS 0.004
CVE-2018-0175
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 arbitrary code with elevated privileges on an affected device. Cisco Bug IDs: CSCvd73664.
Published 2018-03-28 · Analyzed
8.0KEVEPSS 0.035
CVE-2003-0567
Cisco IOS 11.x and 12.0 through 12.2 allows remote attackers to cause a denial of service (traffic block) by sending a particular sequence of IPv4 packets to an interface on the device, causing the input queue on that interface to be marked as full.
Published 2003-07-25 · Modified
7.83 PoCEPSS 0.166
CVE-2002-2315
Cisco IOS 11.2.x and 12.0.x does not limit the size of its redirect table, which allows remote attackers to cause a denial of service (memory consumption) via spoofed ICMP redirect packets to the router.
Published 2007-10-26 · Modified
7.81 PoCEPSS 0.096
CVE-2018-0156
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. The vulnerability is due to improper validation of packet data. An attacker could exploit this vulnerability by sending a crafted packet to an affected device on TCP port 4786. Only Smart Install client switches are affected. Cisco devices that are configured as a Smart Install director are not affected by this vulnerability. Cisco Bug IDs: CSCvd40673.
Published 2018-03-28 · Analyzed
7.8KEVEPSS 0.086
CVE-2018-0154
A vulnerability in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) running Cisco IOS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient handling of VPN traffic by the affected device. An attacker could exploit this vulnerability by sending crafted VPN traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to hang or crash, resulting in a DoS condition. Cisco Bug IDs: CSCvd39267.
Published 2018-03-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2017-12231
A vulnerability in the implementation of Network Address Translation (NAT) functionality in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to the improper translation of H.323 messages that use the Registration, Admission, and Status (RAS) protocol and are sent to an affected device via IPv4 packets. An attacker could exploit this vulnerability by sending a crafted H.323 RAS packet through an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to use an application layer gateway with NAT (NAT ALG) for H.323 RAS messages. By default, a NAT ALG is enabled for H.323 RAS messages. Cisco Bug IDs: CSCvc57217.
Published 2017-09-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2017-12233
Multiple vulnerabilities in the implementation of the Common Industrial Protocol (CIP) feature in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerabilities are due to the improper parsing of crafted CIP packets destined to an affected device. An attacker could exploit these vulnerabilities by sending crafted CIP packets to be processed by an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuz95334.
Published 2017-09-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2017-12234
Multiple vulnerabilities in the implementation of the Common Industrial Protocol (CIP) feature in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerabilities are due to the improper parsing of crafted CIP packets destined to an affected device. An attacker could exploit these vulnerabilities by sending crafted CIP packets to be processed by an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvc43709.
Published 2017-09-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2017-12235
A vulnerability in the implementation of the PROFINET Discovery and Configuration Protocol (PN-DCP) for Cisco IOS 12.2 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to the improper parsing of ingress PN-DCP Identify Request packets destined to an affected device. An attacker could exploit this vulnerability by sending a crafted PN-DCP Identify Request packet to an affected device and then continuing to send normal PN-DCP Identify Request packets to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to process PROFINET messages. Beginning with Cisco IOS Software Release 12.2(52)SE, PROFINET is enabled by default on all the base switch module and expansion-unit Ethernet ports. Cisco Bug IDs: CSCuz47179.
Published 2017-09-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2017-12237
A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco IOS 15.0 through 15.6 and Cisco IOS XE 3.5 through 16.5 could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to how an affected device processes certain IKEv2 packets. An attacker could exploit this vulnerability by sending specific IKEv2 packets to an affected device to be processed. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. This vulnerability affects Cisco devices that have the Internet Security Association and Key Management Protocol (ISAKMP) enabled. Although only IKEv2 packets can be used to trigger this vulnerability, devices that are running Cisco IOS Software or Cisco IOS XE Software are vulnerable when ISAKMP is enabled. A device does not need to be configured with any IKEv2-specific features to be vulnerable. Many features use IKEv2, including different types of VPNs such as the following: LAN-to-LAN VPN; Remote-access VPN, excluding SSL VPN; Dynamic Multipoint VPN (DMVPN); and FlexVPN. Cisco Bug IDs: CSCvc41277.
Published 2017-09-28 · Analyzed
7.8KEVEPSS 0.071
CVE-2018-0159
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 service (DoS) condition. The vulnerability is due to improper validation of specific IKEv1 packets. An attacker could exploit this vulnerability by sending crafted IKEv1 packets to an affected device during an IKE negotiation. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuj73916.
Published 2018-03-28 · Analyzed
7.8KEVEPSS 0.069
CVE-2006-4775
The VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) and CatOS allows remote attackers to cause a denial of service by sending a VTP update with a revision value of 0x7FFFFFFF, which is incremented to 0x80000000 and is interpreted as a negative number in a signed context.
Published 2006-09-14 · Modified
7.8EPSS 0.050
CVE-2006-4774
The VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) allows remote attackers to cause a denial of service by sending a VTP version 1 summary frame with a VTP version field value of 2.
Published 2006-09-14 · Modified
7.8EPSS 0.050
CVE-2016-6382
Cisco IOS 15.2 through 15.6 and IOS XE 3.6 through 3.17 and 16.1 allow remote attackers to cause a denial of service (device restart) via a malformed IPv6 Protocol Independent Multicast (PIM) register packet, aka Bug ID CSCuy16399.
Published 2016-10-05 · Modified
7.8EPSS 0.049
CVE-2002-2208
Extended Interior Gateway Routing Protocol (EIGRP), as implemented in Cisco IOS 11.3 through 12.2 and other products, allows remote attackers to cause a denial of service (flood) by sending a large number of spoofed EIGRP neighbor announcements, which results in an ARP storm on the local network.
Published 2005-12-21 · Modified
7.8EPSS 0.043
CVE-2016-6384
Cisco IOS 12.2 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.17 and 16.2 allow remote attackers to cause a denial of service (device reload) via crafted fields in an H.323 message, aka Bug ID CSCux04257.
Published 2016-10-05 · Modified
7.8EPSS 0.042
CVE-2011-0350
Unspecified vulnerability in Cisco IOS 12.4(24)MD before 12.4(24)MD2 on the Cisco Content Services Gateway Second Generation (aka CSG2) allows remote attackers to cause a denial of service (device hang or reload) via crafted TCP packets, aka Bug ID CSCth41891, a different vulnerability than CVE-2011-0349.
Published 2011-01-28 · Modified
7.8EPSS 0.041
CVE-2011-0349
Unspecified vulnerability in Cisco IOS 12.4(24)MD before 12.4(24)MD2 on the Cisco Content Services Gateway Second Generation (aka CSG2) allows remote attackers to cause a denial of service (device hang or reload) via crafted TCP packets, aka Bug ID CSCth17178, a different vulnerability than CVE-2011-0350.
Published 2011-01-28 · Modified
7.8EPSS 0.041
CVE-2012-0381
The IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x and 3.1.xS through 3.4.xS before 3.4.2S, 3.5.xS before 3.5.1S, and 3.2.xSG before 3.2.2SG allows remote attackers to cause a denial of service (device reload) by sending IKE UDP packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCts38429.
Published 2012-03-29 · Modified
7.8EPSS 0.038
CVE-2012-0382
The Multicast Source Discovery Protocol (MSDP) implementation in Cisco IOS 12.0, 12.2 through 12.4, and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x and 3.1.xS through 3.4.xS before 3.4.1S and 3.1.xSG and 3.2.xSG before 3.2.2SG allows remote attackers to cause a denial of service (device reload) via encapsulated IGMP data in an MSDP packet, aka Bug ID CSCtr28857.
Published 2012-03-29 · Modified
7.8EPSS 0.038
CVE-2015-0646
Memory leak in the TCP input module in Cisco IOS 12.2, 12.4, 15.0, 15.2, 15.3, and 15.4 and IOS XE 3.3.xXO, 3.5.xE, 3.6.xE, 3.8.xS through 3.10.xS before 3.10.5S, and 3.11.xS and 3.12.xS before 3.12.3S allows remote attackers to cause a denial of service (memory consumption or device reload) by sending crafted TCP packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCum94811.
Published 2015-03-26 · Modified
7.8EPSS 0.038
CVE-2016-1351
The Locator/ID Separation Protocol (LISP) implementation in Cisco IOS 15.1 and 15.2 and NX-OS 4.1 through 6.2 allows remote attackers to cause a denial of service (device reload) via a crafted header in a packet, aka Bug ID CSCuu64279.
Published 2016-03-26 · Modified
7.8EPSS 0.037
CVE-2008-1152
The data-link switching (DLSw) component in Cisco IOS 12.0 through 12.4 allows remote attackers to cause a denial of service (device restart or memory consumption) via crafted (1) UDP port 2067 or (2) IP protocol 91 packets.
Published 2008-03-27 · Modified
7.8EPSS 0.037
CVE-2007-0648
Cisco IOS after 12.3(14)T, 12.3(8)YC1, 12.3(8)YG, and 12.4, with voice support and without Session Initiated Protocol (SIP) configured, allows remote attackers to cause a denial of service (crash) by sending a crafted packet to port 5060/UDP.
Published 2007-02-01 · Modified
7.8EPSS 0.036
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