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Cisco IOS

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

620CVEs
CVE-2013-5474
Race condition in the IPv6 virtual fragmentation reassembly (VFR) implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.3 allows remote attackers to cause a denial of service (device reload or hang) via fragmented IPv6 packets, aka Bug ID CSCud64812.
Published 2013-09-27 · Modified
7.8EPSS 0.014
CVE-2013-1145
Memory leak in Cisco IOS 12.2, 12.4, 15.0, and 15.1, when Zone-Based Policy Firewall SIP application layer gateway inspection is enabled, allows remote attackers to cause a denial of service (memory consumption or device reload) via malformed SIP messages, aka Bug ID CSCtl99174.
Published 2013-03-28 · Modified
7.8EPSS 0.013
CVE-2013-1147
The Protocol Translation (PT) functionality in Cisco IOS 12.3 through 12.4 and 15.0 through 15.3, when one-step port-23 translation or a Telnet-to-PAD ruleset is configured, does not properly validate TCP connection information, which allows remote attackers to cause a denial of service (device reload) via an attempted connection to a PT resource, aka Bug ID CSCtz35999.
Published 2013-03-28 · Modified
7.8EPSS 0.013
CVE-2013-1146
The Smart Install client functionality in Cisco IOS 12.2 and 15.0 through 15.3 on Catalyst switches allows remote attackers to cause a denial of service (device reload) via crafted image list parameters in Smart Install packets, aka Bug ID CSCub55790.
Published 2013-03-28 · Modified
7.8EPSS 0.013
CVE-2013-5480
The DNS-over-TCP implementation in Cisco IOS 12.2 and 15.0 through 15.3, when NAT is used, allows remote attackers to cause a denial of service (device reload) via a crafted IPv4 DNS TCP stream, aka Bug ID CSCuf28733.
Published 2013-09-27 · Modified
7.8EPSS 0.013
CVE-2011-0941
Memory leak in Cisco Unified Communications Manager (CUCM) 6.x before 6.1(5)su2, 7.x before 7.1(5b)su3, 8.x before 8.0(3a)su1, and 8.5 before 8.5(1), and Cisco IOS 12.4 and 15.1, allows remote attackers to cause a denial of service (memory consumption and process failure or device reload) via a malformed SIP message, aka Bug IDs CSCti75128 and CSCtj09179.
Published 2011-11-01 · Modified
7.8EPSS 0.012
CVE-2011-1624
Cisco IOS 12.2(58)SE, when a login banner is configured, allows remote attackers to cause a denial of service (device reload) by establishing two SSH2 sessions, aka Bug ID CSCto62631.
Published 2011-08-18 · Modified
7.8EPSS 0.012
CVE-2020-3479
Cisco IOS and IOS XE Software MP-BGP EVPN Denial of Service Vulnerability
Published 2020-09-24 · Modified
7.8EPSS 0.011
CVE-2013-1142
Race condition in the VRF-aware NAT feature in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 allows remote attackers to cause a denial of service (memory consumption) via IPv4 packets, aka Bug IDs CSCtg47129 and CSCtz96745.
Published 2013-03-28 · Modified
7.8EPSS 0.011
CVE-2018-0169
Multiple vulnerabilities in the CLI parser of Cisco IOS XE Software could allow an authenticated, local attacker to gain access to the underlying Linux shell of an affected device and execute arbitrary commands with root privileges on the device. The vulnerabilities are due to the affected software improperly sanitizing command arguments to prevent access to internal data structures on a device. An attacker who has user EXEC mode (privilege level 1) access to an affected device could exploit these vulnerabilities on the device by executing CLI commands that contain crafted arguments. A successful exploit could allow the attacker to gain access to the underlying Linux shell of the affected device and execute arbitrary commands with root privileges on the device. Cisco Bug IDs: CSCtw85441, CSCus42252, CSCuv95370.
Published 2018-03-28 · Modified
7.8EPSS 0.005
CVE-2016-6414
iox in Cisco IOS, possibly 15.6 and earlier, and IOS XE, possibly 3.18 and earlier, allows local users to execute arbitrary IOx Linux commands on the guest OS via crafted iox command-line options, aka Bug ID CSCuz59223.
Published 2016-09-22 · Modified
7.8EPSS 0.004
CVE-2021-1392
Cisco IOS and IOS XE Software Common Industrial Protocol Privilege Escalation Vulnerability
Published 2021-03-24 · Modified
7.8EPSS 0.002
CVE-2025-20352
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 affected device that is running Cisco IOS Software or Cisco IOS XE Software. To cause the DoS, the attacker must have the SNMPv2c or earlier read-only community string or valid SNMPv3 user credentials. An authenticated, remote attacker with high privileges could execute code as the root user on an affected device that is running Cisco IOS XE Software. To execute code as the root user, the attacker must have the SNMPv1 or v2c read-only community string or valid SNMPv3 user credentials and administrative or privilege 15 credentials on the affected device. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device over IPv4 or IPv6 networks. This vulnerability is due to a stack overflow condition in the SNMP subsystem of the affected software. A successful exploit could allow a low-privileged attacker to cause the affected system to reload, resulting in a DoS condition, or allow a high-privileged attacker to execute arbitrary code as the root user and obtain full control of the affected system. Note: This vulnerability affects all versions of SNMP.
Published 2025-09-24 · Analyzed
7.7KEVEPSS 0.394
CVE-2020-3200
Cisco IOS and IOS XE Software Secure Shell Denial of Service Vulnerability
Published 2020-06-03 · Modified
7.7EPSS 0.017
CVE-2020-3235
Cisco IOS and IOS XE Software Simple Network Management Protocol Denial of Service Vulnerability
Published 2020-06-03 · Modified
7.7EPSS 0.016
CVE-2021-34699
Cisco IOS and IOS XE Software TrustSec CLI Parser Denial of Service Vulnerability
Published 2021-09-23 · Modified
7.7EPSS 0.012
CVE-2021-1620
Cisco IOS and IOS XE Software IKEv2 AutoReconnect Feature Denial of Service Vulnerability
Published 2021-09-23 · Analyzed
7.7EPSS 0.011
CVE-2022-20920
Cisco IOS and IOS XE Software SSH Denial of Service Vulnerability
Published 2022-10-10 · Modified
7.7EPSS 0.009
CVE-2025-20170
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20171
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20169
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20172
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 when parsing SNMP requests. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. For Cisco IOS and IOS XE Software, a successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. For Cisco IOS XR Software, a successful exploit could allow the attacker to cause the SNMP process to restart, resulting in an interrupted SNMP response from an affected device. Devices that are running Cisco IOS XR Software will not reload.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20173
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20176
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20174
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20175
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. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.
Published 2025-02-05 · Analyzed
7.7EPSS 0.008
CVE-2025-20327
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 exploit this vulnerability by sending a crafted URL in an HTTP request. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
Published 2025-09-24 · Analyzed
7.7EPSS 0.004
CVE-2009-2865
Buffer overflow in the login implementation in the Extension Mobility feature in the Unified Communications Manager Express (CME) component in Cisco IOS 12.4XW, 12.4XY, 12.4XZ, and 12.4YA allows remote attackers to execute arbitrary code or cause a denial of service via crafted HTTP requests, aka Bug ID CSCsq58779.
Published 2009-09-28 · Modified
7.6EPSS 0.055
CVE-2022-20724
Cisco IOx Application Hosting Environment Vulnerabilities
Published 2022-04-15 · Modified
7.6EPSS 0.013
CVE-2016-6415
The server IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.6, IOS XE through 3.18S, IOS XR 4.3.x and 5.0.x through 5.2.x, and PIX before 7.0 allows remote attackers to obtain sensitive information from device memory via a Security Association (SA) negotiation request, aka Bug IDs CSCvb29204 and CSCvb36055 or BENIGNCERTAIN.
Published 2016-09-19 · Analyzed
7.5KEV1 PoCEPSS 0.877
CVE-2005-2841
Buffer overflow in Firewall Authentication Proxy for FTP and/or Telnet Sessions for Cisco IOS 12.2ZH and 12.2ZL, 12.3 and 12.3T, and 12.4 and 12.4T allows remote attackers to cause a denial of service and possibly execute arbitrary code via crafted user authentication credentials.
Published 2005-09-08 · Modified
7.51 PoCEPSS 0.141
CVE-2003-0100
Buffer overflow in Cisco IOS 11.2.x to 12.0.x allows remote attackers to cause a denial of service and possibly execute commands via a large number of OSPF neighbor announcements.
Published 2004-09-01 · Modified
7.51 PoCEPSS 0.096
CVE-2004-0079
The do_change_cipher_spec function in OpenSSL 0.9.6c to 0.9.6k, and 0.9.7a to 0.9.7c, allows remote attackers to cause a denial of service (crash) via a crafted SSL/TLS handshake that triggers a null dereference.
Published 2004-03-18 · Modified
7.5EPSS 0.095
CVE-2006-4776
Heap-based buffer overflow in the VLAN Trunking Protocol (VTP) feature in Cisco IOS 12.1(19) allows remote attackers to execute arbitrary code via a long VLAN name in a VTP type 2 summary advertisement.
Published 2006-09-14 · Modified
7.5EPSS 0.078
CVE-2003-1109
The Session Initiation Protocol (SIP) implementation in multiple Cisco products including IP Phone models 7940 and 7960, IOS versions in the 12.2 train, and Secure PIX 5.2.9 to 6.2.2 allows remote attackers to cause a denial of service and possibly execute arbitrary code via crafted INVITE messages, as demonstrated by the OUSPG PROTOS c07-sip test suite.
Published 2005-03-11 · Modified
7.5EPSS 0.068
CVE-2017-6627
A vulnerability in the UDP processing code of Cisco IOS 15.1, 15.2, and 15.4 and IOS XE 3.14 through 3.18 could allow an unauthenticated, remote attacker to cause the input queue of an affected system to hold UDP packets, causing an interface queue wedge and a denial of service (DoS) condition. The vulnerability is due to Cisco IOS Software application changes that create UDP sockets and leave the sockets idle without closing them. An attacker could exploit this vulnerability by sending UDP packets with a destination port of 0 to an affected device. A successful exploit could allow the attacker to cause UDP packets to be held in the input interfaces queue, resulting in a DoS condition. The input interface queue will stop holding UDP packets when it receives 250 packets. Cisco Bug IDs: CSCup10024, CSCva55744, CSCva95506.
Published 2017-09-07 · Analyzed
7.5KEVEPSS 0.062
CVE-2003-0647
Buffer overflow in the HTTP server for Cisco IOS 12.2 and earlier allows remote attackers to execute arbitrary code via an extremely long (2GB) HTTP GET request.
Published 2003-08-05 · Modified
7.51 PoCEPSS 0.059
CVE-2001-0288
Cisco switches and routers running IOS 12.1 and earlier produce predictable TCP Initial Sequence Numbers (ISNs), which allows remote attackers to spoof or hijack TCP connections.
Published 2001-05-07 · Modified
7.51 PoCEPSS 0.054
CVE-2016-6393
The AAA service in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.1 through 3.18 and 16.2 allows remote attackers to cause a denial of service (device reload) via a failed SSH connection attempt that is mishandled during generation of an error-log message, aka Bug ID CSCuy87667.
Published 2016-10-05 · Modified
7.5EPSS 0.046
CVE-2004-0054
Multiple vulnerabilities in the H.323 protocol implementation for Cisco IOS 11.3T through 12.2T allow remote attackers to cause a denial of service and possibly execute arbitrary code, as demonstrated by the NISCC/OUSPG PROTOS test suite for the H.225 protocol.
Published 2004-01-15 · Modified
7.5EPSS 0.046
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