Cisco IOS vulnerabilities
16 known CVE vulnerabilities in Cisco IOS, translated and rated.
- CVE-2016-1478High
Cisco IOS versions 15.5(3)S3, 15.6(1)S2, 15.6(2)S1, and 15.6(2)T1 improperly dequeue invalid NTP packets, allowing remote attackers to cause a denial of service (interface wedge) by sending many crafted NTP packets.
- CVE-2015-0649High
Cisco IOS versions 12.2, 12.4, 15.0, 15.2, and 15.3 allow remote attackers to cause a denial of service (device reload) via malformed Common Industrial Protocol (CIP) TCP packets.
- CVE-2015-0647High
Cisco IOS versions 12.2, 12.4, 15.0, 15.2, and 15.3 allow remote attackers to cause a denial of service (device reload) via malformed Common Industrial Protocol (CIP) UDP packets.
- CVE-2015-0638High
In Cisco IOS versions 12.2, 12.4, 15.0, 15.2, and 15.3, configuring a VRF interface allows remote attackers to cause a denial of service (interface queue wedge) via crafted ICMPv4 packets.
- CVE-2017-12238MediumActively exploited
A vulnerability in the Virtual Private LAN Service (VPLS) code of Cisco IOS 15.0 through 15.4 for Cisco Catalyst 6800 Series Switches allows an unauthenticated, adjacent attacker to crash a C6800-16P10G or C6800-16P10G-XL line card, causing a denial of service (DoS). It stems from a memory management issue; the attacker creates a large number of VPLS-generated MAC entries in the MAC address table.
- CVE-2017-12232MediumActively exploited
A vulnerability in the implementation of a protocol in Cisco Integrated Services Routers Generation 2 (ISR G2) Routers running Cisco IOS 15.0 through 15.6 allows an unauthenticated, adjacent attacker to cause an affected device to reload, resulting in a denial of service (DoS). It is due to misclassification of Ethernet frames; the attacker sends a crafted Ethernet frame.
- CVE-2008-4128HighActively exploited
Multiple CSRF vulnerabilities in the HTTP Administration component of Cisco IOS 12.4 on the 871 Integrated Services Router allow remote attackers to execute arbitrary commands. The attack involves requests to the /level/15/exec/- URI with the "show privilege" command and to the /level/15/exec/-/configure/http URI with the "alias exec" command.
- CVE-2004-1464MediumActively exploited
Cisco IOS 12.2(15) and earlier allows remote attackers to cause a denial of service (refused VTY (virtual terminal) connections), via a crafted TCP connection to the Telnet or reverse Telnet port.
- CVE-2000-0984Medium
The HTTP server in Cisco IOS 12.0 through 12.1 allows local users to cause a denial of service (crash and reload) via a URL containing a "?/" string.
- CVE-1999-0063Medium
Cisco IOS 12.0 and other versions can be crashed by malicious UDP packets to the syslog port.
- CVE-2025-20149Medium
A vulnerability in the CLI of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This is due to a buffer overflow, and an attacker with a low-privileged account could exploit it using crafted commands.
- CVE-1999-0445Medium
In some versions of IOS 12.0 on Cisco routers running NAT, some packets may not be filtered by input access list filters.
- CVE-1999-0162Medium
The 'established' keyword in some Cisco IOS software allowed an attacker to bypass filtering.
- CVE-1999-0159Low
Attackers can crash a Cisco IOS router or device, provided they can get to an interactive prompt (such as a login). This applies to some IOS 9.x, 10.x, and 11.x releases.
- CVE-1999-0160High
Some classic Cisco IOS devices have a vulnerability in PPP CHAP authentication, allowing unauthorized PPP connections to be established.
- CVE-1999-0161High
In Cisco IOS 10.3, with the tacacs-ds or tacacs keyword, an extended IP access control list could bypass filtering.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS