CVE-2026-20301: Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol

Description

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 on an affected device. This vulnerability is due to improper handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Cisco Cisco IOS XE Software

Default version status: unknown

17.2.1aaffected
16.12.1yaffected
16.12.3saffected
16.7.1baffected
16.6.2affected
16.6.5affected
16.12.1waffected
16.9.1daffected
17.3.1affected
16.9.4caffected
16.7.1affected
17.2.1affected
16.6.8affected
16.9.1baffected
16.9.2saffected
16.12.4affected
16.12.3aaffected
17.1.1saffected
16.11.1aaffected
16.7.2affected
16.11.1baffected
16.9.1saffected
16.9.3haffected
16.9.1caffected
16.6.5aaffected
16.6.3affected
16.10.1faffected
17.2.1vaffected
16.8.1eaffected
16.9.3aaffected
16.12.1aaffected
16.12.1xaffected
3.16.10aSaffected
16.6.4saffected
16.10.1caffected
16.12.3affected
16.11.2affected
16.6.5baffected
16.12.2saffected
16.10.1baffected
16.7.3affected
16.6.7affected
16.9.6affected
16.9.2affected
16.10.1affected
16.12.1taffected
16.9.1affected
16.8.1aaffected
3.18.8aSPaffected
16.9.3saffected
16.6.7aaffected
16.12.2affected
16.11.1affected
16.9.3affected
16.11.1saffected
16.12.1affected
17.1.1affected
17.1.2affected
16.10.1daffected
17.1.1taffected
16.9.4affected
16.8.3affected
16.12.2taffected
16.9.5affected
16.8.1saffected
16.10.1eaffected
16.8.2affected
16.6.4affected
16.8.1baffected
16.10.1aaffected
16.12.1zaffected
16.8.1caffected
16.9.1aaffected
16.9.5faffected
16.6.4aaffected
16.10.1gaffected
16.8.1affected
16.6.6affected
16.9.2aaffected
16.8.1daffected
16.10.3affected
16.7.1aaffected
16.11.1caffected
16.10.1saffected
17.2.1raffected
17.1.1aaffected
16.10.2affected
16.12.2aaffected
16.12.1caffected
16.12.1saffected
16.7.4affected
3.18.9SPaffected
17.2.2affected
3.11.3Eaffected
16.9.8affected
16.9.7affected
17.1.3affected
17.3.1aaffected
3.11.4Eaffected
17.3.2aaffected
16.12.5affected
17.3.1waffected
17.3.2affected
3.11.3aEaffected
17.4.1affected
16.12.4aaffected
17.4.1aaffected
3.16.10bSaffected
17.3.1xaffected
17.3.3affected
16.6.9affected
17.2.3affected
17.5.1affected
16.12.1z1affected
16.12.5aaffected
17.4.1baffected
17.3.1zaffected
16.12.5baffected
17.4.2affected
17.3.3aaffected
3.11.5Eaffected
17.3.5affected
17.3.4affected
17.5.1aaffected
16.12.6affected
17.6.1affected
16.12.1z2affected
16.6.10affected
17.3.4aaffected
17.6.1aaffected
3.8.10cEaffected
17.7.1affected
17.6.1xaffected
17.6.2affected
16.12.6aaffected
17.3.4caffected
17.4.2aaffected
17.3.4baffected
17.7.1aaffected
16.12.7affected
17.8.1aaffected
17.6.3aaffected
17.6.3affected
17.7.2affected
17.7.1baffected
17.9.1waffected
17.3.5aaffected
17.6.1zaffected
3.8.10dEaffected
16.12.8affected
17.8.1affected
17.9.1affected
3.11.6Eaffected
17.6.4affected
3.11.7Eaffected
17.3.5baffected
17.9.1aaffected
17.3.6affected
17.10.1affected
3.11.8Eaffected
16.9.8aaffected
17.6.1z1affected
17.10.1aaffected
17.9.2affected
17.6.5affected
17.9.1xaffected
17.9.1yaffected
16.9.8baffected
17.3.7affected
17.9.2aaffected
17.9.3affected
16.12.9affected
17.11.1affected
17.10.1baffected
17.6.6affected
17.9.1x1affected
17.11.1aaffected
17.9.3aaffected
17.12.1affected
17.3.8affected
17.9.4affected
16.12.10affected
17.12.1waffected
17.9.1y1affected
17.12.1aaffected
3.11.9Eaffected
17.9.5affected
17.13.1affected
17.12.1xaffected
17.12.2affected
17.14.1affected
17.9.4aaffected
17.3.8aaffected
17.6.6aaffected
17.6.5aaffected
17.6.7affected
16.12.10aaffected
17.15.1affected
17.13.1aaffected
17.12.2aaffected
16.12.11affected
17.12.3affected
17.12.1yaffected
3.11.10Eaffected
17.12.1zaffected
17.9.5aaffected
17.14.1aaffected
17.9.5baffected
17.6.8affected
16.12.12affected
17.12.4affected
17.9.6affected
17.17.1affected
17.16.1affected
17.15.1waffected
17.12.3aaffected
3.11.11Eaffected
17.9.5caffected
17.15.1aaffected
17.12.1z1affected
17.15.2affected
17.15.1baffected
17.9.5daffected
17.15.1xaffected
17.9.6aaffected
17.12.1z2affected
17.6.8aaffected
17.16.1aaffected
16.12.13affected
17.15.3affected
17.9.7affected
17.12.5affected
17.15.1yaffected
17.9.5eaffected
17.12.4aaffected
17.15.2aaffected
17.15.2caffected
17.15.2baffected
17.12.1z3affected
17.9.5faffected
17.12.4baffected
3.11.12Eaffected
17.12.5aaffected
17.18.1affected
17.12.6affected
17.12.1z4affected
17.9.8affected
17.9.7aaffected
17.15.3aaffected
17.15.4affected
3.11.13Eaffected
17.12.5baffected
17.15.3baffected
16.12.14affected
17.18.1zaffected
17.9.7baffected
17.12.5caffected
26.1.1affected
17.18.1aaffected
17.15.4aaffected
17.18.2affected
17.18.1waffected
17.15.4baffected
17.12.6aaffected
17.12.7affected
17.15.4caffected
17.9.9affected
17.12.5daffected
16.12.15affected
17.15.4s1affected
17.15.5affected
17.12.1z5affected
17.18.1xaffected
17.12.1z6affected
17.15.4daffected
17.12.6baffected
17.4.1caffected
3.11.14Eaffected
17.15.5aaffected
17.18.1yaffected
17.12.7aaffected
17.18.3affected
17.12.7baffected
17.18.3aaffected
26.1.1aaffected
26.2.1eaaffected
16.12.16affected

Cisco IOS

Default version status: unknown

15.2(7)E7affected
15.2(8)E3affected
15.7(3)M10affected
15.8(3)M9affected
15.9(3)M7affected
15.2(7)E8affected
15.2(8)E4affected
15.9(3)M7aaffected
15.2(2)E10caffected
15.2(4)E10daffected
15.9(3)M6aaffected
15.9(3)M6baffected
15.5(1)SY10affected
15.5(1)SY11affected
15.2(6)E1aaffected
15.4(1)SY4affected
15.5(1)SY1affected
15.2(2)E8affected
15.2(6)E1affected
15.7(3)M2affected
15.2(4)E6affected
15.2(1)SY6affected
15.2(4)EA7affected
15.2(6)E1saffected
15.7(3)M3affected
15.8(3)Maffected
15.2(1)SY7affected
15.2(4)EA8affected
15.8(3)M0aaffected
15.2(2)E9affected
15.2(6)E2affected
15.5(1)SY2affected
15.2(4)E7affected
15.2(6)E2aaffected
15.2(2)E9aaffected
15.8(3)M0baffected
15.2(6)E2baffected
15.8(3)M1affected
15.8(3)M1aaffected
15.7(3)M4affected
15.2(1)SY8affected
15.2(4)E8affected
15.5(1)SY3affected
15.2(7)Eaffected
15.7(3)M4aaffected
15.8(3)M2affected
15.2(7)E0aaffected
15.8(3)M2aaffected
15.7(3)M4baffected
15.2(2)E10affected
15.2(7)E0saffected
15.2(4)EA9affected
15.2(7)E0baffected
15.2(6)E3affected
15.9(3)Maffected
15.8(3)M3affected
15.5(1)SY4affected
15.7(3)M5affected
15.2(2)E10aaffected
15.2(4)E9affected
15.2(7)E1affected
15.8(3)M3baffected
15.9(3)M0aaffected
15.2(7)E1aaffected
15.2(4)E10affected
15.5(1)SY5affected
15.2(4)EA9aaffected
15.9(3)M1affected
15.8(3)M4affected
15.7(3)M6affected
15.2(7)E2affected
15.5(1)SY6affected
15.2(7)E3affected
15.8(3)M5affected
15.7(3)M7affected
15.9(3)M2affected
15.2(7)E2baffected
15.9(3)M2aaffected
15.2(4)E10aaffected
15.2(7)E4affected
15.5(1)SY7affected
15.2(4)E10baffected
15.2(7)E3kaffected
15.2(8)Eaffected
15.9(3)M3affected
15.8(3)M6affected
15.7(3)M8affected
15.8(3)M7affected
15.5(1)SY8affected
15.2(7)E5affected
15.2(8)E1affected
15.9(3)M4affected
15.2(8)E2affected
15.2(4)E10caffected
15.7(3)M9affected
15.2(2)E10baffected
15.2(7)E6affected
15.9(3)M4aaffected
15.5(1)SY9affected
15.9(3)M5affected
15.8(3)M8affected
15.9(3)M6affected
15.9(3)M9affected
15.5(1)SY13affected
15.9(3)M8baffected
15.2(7)E9affected
15.5(1)SY12affected
15.7(3)M10aaffected
15.9(3)M8affected
15.9(3)M8aaffected
15.2(8)E5affected
15.2(7)E10affected
15.7(3)M10baffected
15.9(3)M3aaffected
15.8(3)M3aaffected
15.9(3)M3baffected
15.6(2)SP7affected
15.6(2)SP5affected
15.6(2)SP8affected
15.6(2)SP6affected
15.6(2)SP4affected
15.6(2)SP9affected
15.6(2)SP8aaffected
15.9(3)M9aaffected
15.2(8)E6affected
15.9(3)M10affected
15.2(7)E11affected
15.5(1)SY14affected
15.2(8)E7affected
15.2(4)E10eaffected
15.9(3)M11affected
15.2(7)E12affected
15.5(1)SY15affected
15.2(8)E8affected
15.5(1)SY16affected
15.2(7)E13affected
15.9(3)M12affected
15.5(1)SY17affected
15.2(7)E14affected
15.9(3)M13affected

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xmcp-thbAr34t ↗