CVE-2026-20301 — Cisco IOS Software and IOS XE Software Extensible Messaging Client Protocol Denial of Service Vulnerability

Description (CNA)

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 (CNA)

Vendor / product	Versions
Cisco / Cisco IOS XE Software	affected 17.2.1a; affected 16.12.1y; affected 16.12.3s; affected 16.7.1b; affected 16.6.2; affected 16.6.5; affected 16.12.1w; affected 16.9.1d; affected 17.3.1; affected 16.9.4c; affected 16.7.1; affected 17.2.1; affected 16.6.8; affected 16.9.1b; affected 16.9.2s; affected 16.12.4; affected 16.12.3a; affected 17.1.1s; affected 16.11.1a; affected 16.7.2; affected 16.11.1b; affected 16.9.1s; affected 16.9.3h; affected 16.9.1c; affected 16.6.5a; affected 16.6.3; affected 16.10.1f; affected 17.2.1v; affected 16.8.1e; affected 16.9.3a; affected 16.12.1a; affected 16.12.1x; affected 3.16.10aS; affected 16.6.4s; affected 16.10.1c; affected 16.12.3; affected 16.11.2; affected 16.6.5b; affected 16.12.2s; affected 16.10.1b; affected 16.7.3; affected 16.6.7; affected 16.9.6; affected 16.9.2; affected 16.10.1; affected 16.12.1t; affected 16.9.1; affected 16.8.1a; affected 3.18.8aSP; affected 16.9.3s; affected 16.6.7a; affected 16.12.2; affected 16.11.1; affected 16.9.3; affected 16.11.1s; affected 16.12.1; affected 17.1.1; affected 17.1.2; affected 16.10.1d; affected 17.1.1t; affected 16.9.4; affected 16.8.3; affected 16.12.2t; affected 16.9.5; affected 16.8.1s; affected 16.10.1e; affected 16.8.2; affected 16.6.4; affected 16.8.1b; affected 16.10.1a; affected 16.12.1z; affected 16.8.1c; affected 16.9.1a; affected 16.9.5f; affected 16.6.4a; affected 16.10.1g; affected 16.8.1; affected 16.6.6; affected 16.9.2a; affected 16.8.1d; affected 16.10.3; affected 16.7.1a; affected 16.11.1c; affected 16.10.1s; affected 17.2.1r; affected 17.1.1a; affected 16.10.2; affected 16.12.2a; affected 16.12.1c; affected 16.12.1s; affected 16.7.4; affected 3.18.9SP; affected 17.2.2; affected 3.11.3E; affected 16.9.8; affected 16.9.7; affected 17.1.3; affected 17.3.1a; affected 3.11.4E; affected 17.3.2a; affected 16.12.5; affected 17.3.1w; affected 17.3.2; affected 3.11.3aE; affected 17.4.1; affected 16.12.4a; affected 17.4.1a; affected 3.16.10bS; affected 17.3.1x; affected 17.3.3; affected 16.6.9; affected 17.2.3; affected 17.5.1; affected 16.12.1z1; affected 16.12.5a; affected 17.4.1b; affected 17.3.1z; affected 16.12.5b; affected 17.4.2; affected 17.3.3a; affected 3.11.5E; affected 17.3.5; affected 17.3.4; affected 17.5.1a; affected 16.12.6; affected 17.6.1; affected 16.12.1z2; affected 16.6.10; affected 17.3.4a; affected 17.6.1a; affected 3.8.10cE; affected 17.7.1; affected 17.6.1x; affected 17.6.2; affected 16.12.6a; affected 17.3.4c; affected 17.4.2a; affected 17.3.4b; affected 17.7.1a; affected 16.12.7; affected 17.8.1a; affected 17.6.3a; affected 17.6.3; affected 17.7.2; affected 17.7.1b; affected 17.9.1w; affected 17.3.5a; affected 17.6.1z; affected 3.8.10dE; affected 16.12.8; affected 17.8.1; affected 17.9.1; affected 3.11.6E; affected 17.6.4; affected 3.11.7E; affected 17.3.5b; affected 17.9.1a; affected 17.3.6; affected 17.10.1; affected 3.11.8E; affected 16.9.8a; affected 17.6.1z1; affected 17.10.1a; affected 17.9.2; affected 17.6.5; affected 17.9.1x; affected 17.9.1y; affected 16.9.8b; affected 17.3.7; affected 17.9.2a; affected 17.9.3; affected 16.12.9; affected 17.11.1; affected 17.10.1b; affected 17.6.6; affected 17.9.1x1; affected 17.11.1a; affected 17.9.3a; affected 17.12.1; affected 17.3.8; affected 17.9.4; affected 16.12.10; affected 17.12.1w; affected 17.9.1y1; affected 17.12.1a; affected 3.11.9E; affected 17.9.5; affected 17.13.1; affected 17.12.1x; affected 17.12.2; affected 17.14.1; affected 17.9.4a; affected 17.3.8a; affected 17.6.6a; affected 17.6.5a; affected 17.6.7; affected 16.12.10a; affected 17.15.1; affected 17.13.1a; affected 17.12.2a; affected 16.12.11; affected 17.12.3; affected 17.12.1y; affected 3.11.10E; affected 17.12.1z; affected 17.9.5a; affected 17.14.1a; affected 17.9.5b; affected 17.6.8; affected 16.12.12; affected 17.12.4; affected 17.9.6; affected 17.17.1; affected 17.16.1; affected 17.15.1w; affected 17.12.3a; affected 3.11.11E; affected 17.9.5c; affected 17.15.1a; affected 17.12.1z1; affected 17.15.2; affected 17.15.1b; affected 17.9.5d; affected 17.15.1x; affected 17.9.6a; affected 17.12.1z2; affected 17.6.8a; affected 17.16.1a; affected 16.12.13; affected 17.15.3; affected 17.9.7; affected 17.12.5; affected 17.15.1y; affected 17.9.5e; affected 17.12.4a; affected 17.15.2a; affected 17.15.2c; affected 17.15.2b; affected 17.12.1z3; affected 17.9.5f; affected 17.12.4b; affected 3.11.12E; affected 17.12.5a; affected 17.18.1; affected 17.12.6; affected 17.12.1z4; affected 17.9.8; affected 17.9.7a; affected 17.15.3a; affected 17.15.4; affected 3.11.13E; affected 17.12.5b; affected 17.15.3b; affected 16.12.14; affected 17.18.1z; affected 17.9.7b; affected 17.12.5c; affected 26.1.1; affected 17.18.1a; affected 17.15.4a; affected 17.18.2; affected 17.18.1w; affected 17.15.4b; affected 17.12.6a; affected 17.12.7; affected 17.15.4c; affected 17.9.9; affected 17.12.5d; affected 16.12.15; affected 17.15.4s1; affected 17.15.5; affected 17.12.1z5; affected 17.18.1x; affected 17.12.1z6; affected 17.15.4d; affected 17.12.6b; affected 17.4.1c; affected 3.11.14E; affected 17.15.5a; affected 17.18.1y; affected 17.12.7a; affected 17.18.3; affected 17.12.7b; affected 17.18.3a; affected 26.1.1a; affected 26.2.1ea; affected 16.12.16
Cisco / IOS	affected 15.2(7)E7; affected 15.2(8)E3; affected 15.7(3)M10; affected 15.8(3)M9; affected 15.9(3)M7; affected 15.2(7)E8; affected 15.2(8)E4; affected 15.9(3)M7a; affected 15.2(2)E10c; affected 15.2(4)E10d; affected 15.9(3)M6a; affected 15.9(3)M6b; affected 15.5(1)SY10; affected 15.5(1)SY11; affected 15.2(6)E1a; affected 15.4(1)SY4; affected 15.5(1)SY1; affected 15.2(2)E8; affected 15.2(6)E1; affected 15.7(3)M2; affected 15.2(4)E6; affected 15.2(1)SY6; affected 15.2(4)EA7; affected 15.2(6)E1s; affected 15.7(3)M3; affected 15.8(3)M; affected 15.2(1)SY7; affected 15.2(4)EA8; affected 15.8(3)M0a; affected 15.2(2)E9; affected 15.2(6)E2; affected 15.5(1)SY2; affected 15.2(4)E7; affected 15.2(6)E2a; affected 15.2(2)E9a; affected 15.8(3)M0b; affected 15.2(6)E2b; affected 15.8(3)M1; affected 15.8(3)M1a; affected 15.7(3)M4; affected 15.2(1)SY8; affected 15.2(4)E8; affected 15.5(1)SY3; affected 15.2(7)E; affected 15.7(3)M4a; affected 15.8(3)M2; affected 15.2(7)E0a; affected 15.8(3)M2a; affected 15.7(3)M4b; affected 15.2(2)E10; affected 15.2(7)E0s; affected 15.2(4)EA9; affected 15.2(7)E0b; affected 15.2(6)E3; affected 15.9(3)M; affected 15.8(3)M3; affected 15.5(1)SY4; affected 15.7(3)M5; affected 15.2(2)E10a; affected 15.2(4)E9; affected 15.2(7)E1; affected 15.8(3)M3b; affected 15.9(3)M0a; affected 15.2(7)E1a; affected 15.2(4)E10; affected 15.5(1)SY5; affected 15.2(4)EA9a; affected 15.9(3)M1; affected 15.8(3)M4; affected 15.7(3)M6; affected 15.2(7)E2; affected 15.5(1)SY6; affected 15.2(7)E3; affected 15.8(3)M5; affected 15.7(3)M7; affected 15.9(3)M2; affected 15.2(7)E2b; affected 15.9(3)M2a; affected 15.2(4)E10a; affected 15.2(7)E4; affected 15.5(1)SY7; affected 15.2(4)E10b; affected 15.2(7)E3k; affected 15.2(8)E; affected 15.9(3)M3; affected 15.8(3)M6; affected 15.7(3)M8; affected 15.8(3)M7; affected 15.5(1)SY8; affected 15.2(7)E5; affected 15.2(8)E1; affected 15.9(3)M4; affected 15.2(8)E2; affected 15.2(4)E10c; affected 15.7(3)M9; affected 15.2(2)E10b; affected 15.2(7)E6; affected 15.9(3)M4a; affected 15.5(1)SY9; affected 15.9(3)M5; affected 15.8(3)M8; affected 15.9(3)M6; affected 15.9(3)M9; affected 15.5(1)SY13; affected 15.9(3)M8b; affected 15.2(7)E9; affected 15.5(1)SY12; affected 15.7(3)M10a; affected 15.9(3)M8; affected 15.9(3)M8a; affected 15.2(8)E5; affected 15.2(7)E10; affected 15.7(3)M10b; affected 15.9(3)M3a; affected 15.8(3)M3a; affected 15.9(3)M3b; affected 15.6(2)SP7; affected 15.6(2)SP5; affected 15.6(2)SP8; affected 15.6(2)SP6; affected 15.6(2)SP4; affected 15.6(2)SP9; affected 15.6(2)SP8a; affected 15.9(3)M9a; affected 15.2(8)E6; affected 15.9(3)M10; affected 15.2(7)E11; affected 15.5(1)SY14; affected 15.2(8)E7; affected 15.2(4)E10e; affected 15.9(3)M11; affected 15.2(7)E12; affected 15.5(1)SY15; affected 15.2(8)E8; affected 15.5(1)SY16; affected 15.2(7)E13; affected 15.9(3)M12; affected 15.5(1)SY17; affected 15.2(7)E14; affected 15.9(3)M13

Vendor / product

Versions

Cisco / Cisco IOS XE Software

affected 17.2.1a; affected 16.12.1y; affected 16.12.3s; affected 16.7.1b; affected 16.6.2; affected 16.6.5; affected 16.12.1w; affected 16.9.1d; affected 17.3.1; affected 16.9.4c; affected 16.7.1; affected 17.2.1; affected 16.6.8; affected 16.9.1b; affected 16.9.2s; affected 16.12.4; affected 16.12.3a; affected 17.1.1s; affected 16.11.1a; affected 16.7.2; affected 16.11.1b; affected 16.9.1s; affected 16.9.3h; affected 16.9.1c; affected 16.6.5a; affected 16.6.3; affected 16.10.1f; affected 17.2.1v; affected 16.8.1e; affected 16.9.3a; affected 16.12.1a; affected 16.12.1x; affected 3.16.10aS; affected 16.6.4s; affected 16.10.1c; affected 16.12.3; affected 16.11.2; affected 16.6.5b; affected 16.12.2s; affected 16.10.1b; affected 16.7.3; affected 16.6.7; affected 16.9.6; affected 16.9.2; affected 16.10.1; affected 16.12.1t; affected 16.9.1; affected 16.8.1a; affected 3.18.8aSP; affected 16.9.3s; affected 16.6.7a; affected 16.12.2; affected 16.11.1; affected 16.9.3; affected 16.11.1s; affected 16.12.1; affected 17.1.1; affected 17.1.2; affected 16.10.1d; affected 17.1.1t; affected 16.9.4; affected 16.8.3; affected 16.12.2t; affected 16.9.5; affected 16.8.1s; affected 16.10.1e; affected 16.8.2; affected 16.6.4; affected 16.8.1b; affected 16.10.1a; affected 16.12.1z; affected 16.8.1c; affected 16.9.1a; affected 16.9.5f; affected 16.6.4a; affected 16.10.1g; affected 16.8.1; affected 16.6.6; affected 16.9.2a; affected 16.8.1d; affected 16.10.3; affected 16.7.1a; affected 16.11.1c; affected 16.10.1s; affected 17.2.1r; affected 17.1.1a; affected 16.10.2; affected 16.12.2a; affected 16.12.1c; affected 16.12.1s; affected 16.7.4; affected 3.18.9SP; affected 17.2.2; affected 3.11.3E; affected 16.9.8; affected 16.9.7; affected 17.1.3; affected 17.3.1a; affected 3.11.4E; affected 17.3.2a; affected 16.12.5; affected 17.3.1w; affected 17.3.2; affected 3.11.3aE; affected 17.4.1; affected 16.12.4a; affected 17.4.1a; affected 3.16.10bS; affected 17.3.1x; affected 17.3.3; affected 16.6.9; affected 17.2.3; affected 17.5.1; affected 16.12.1z1; affected 16.12.5a; affected 17.4.1b; affected 17.3.1z; affected 16.12.5b; affected 17.4.2; affected 17.3.3a; affected 3.11.5E; affected 17.3.5; affected 17.3.4; affected 17.5.1a; affected 16.12.6; affected 17.6.1; affected 16.12.1z2; affected 16.6.10; affected 17.3.4a; affected 17.6.1a; affected 3.8.10cE; affected 17.7.1; affected 17.6.1x; affected 17.6.2; affected 16.12.6a; affected 17.3.4c; affected 17.4.2a; affected 17.3.4b; affected 17.7.1a; affected 16.12.7; affected 17.8.1a; affected 17.6.3a; affected 17.6.3; affected 17.7.2; affected 17.7.1b; affected 17.9.1w; affected 17.3.5a; affected 17.6.1z; affected 3.8.10dE; affected 16.12.8; affected 17.8.1; affected 17.9.1; affected 3.11.6E; affected 17.6.4; affected 3.11.7E; affected 17.3.5b; affected 17.9.1a; affected 17.3.6; affected 17.10.1; affected 3.11.8E; affected 16.9.8a; affected 17.6.1z1; affected 17.10.1a; affected 17.9.2; affected 17.6.5; affected 17.9.1x; affected 17.9.1y; affected 16.9.8b; affected 17.3.7; affected 17.9.2a; affected 17.9.3; affected 16.12.9; affected 17.11.1; affected 17.10.1b; affected 17.6.6; affected 17.9.1x1; affected 17.11.1a; affected 17.9.3a; affected 17.12.1; affected 17.3.8; affected 17.9.4; affected 16.12.10; affected 17.12.1w; affected 17.9.1y1; affected 17.12.1a; affected 3.11.9E; affected 17.9.5; affected 17.13.1; affected 17.12.1x; affected 17.12.2; affected 17.14.1; affected 17.9.4a; affected 17.3.8a; affected 17.6.6a; affected 17.6.5a; affected 17.6.7; affected 16.12.10a; affected 17.15.1; affected 17.13.1a; affected 17.12.2a; affected 16.12.11; affected 17.12.3; affected 17.12.1y; affected 3.11.10E; affected 17.12.1z; affected 17.9.5a; affected 17.14.1a; affected 17.9.5b; affected 17.6.8; affected 16.12.12; affected 17.12.4; affected 17.9.6; affected 17.17.1; affected 17.16.1; affected 17.15.1w; affected 17.12.3a; affected 3.11.11E; affected 17.9.5c; affected 17.15.1a; affected 17.12.1z1; affected 17.15.2; affected 17.15.1b; affected 17.9.5d; affected 17.15.1x; affected 17.9.6a; affected 17.12.1z2; affected 17.6.8a; affected 17.16.1a; affected 16.12.13; affected 17.15.3; affected 17.9.7; affected 17.12.5; affected 17.15.1y; affected 17.9.5e; affected 17.12.4a; affected 17.15.2a; affected 17.15.2c; affected 17.15.2b; affected 17.12.1z3; affected 17.9.5f; affected 17.12.4b; affected 3.11.12E; affected 17.12.5a; affected 17.18.1; affected 17.12.6; affected 17.12.1z4; affected 17.9.8; affected 17.9.7a; affected 17.15.3a; affected 17.15.4; affected 3.11.13E; affected 17.12.5b; affected 17.15.3b; affected 16.12.14; affected 17.18.1z; affected 17.9.7b; affected 17.12.5c; affected 26.1.1; affected 17.18.1a; affected 17.15.4a; affected 17.18.2; affected 17.18.1w; affected 17.15.4b; affected 17.12.6a; affected 17.12.7; affected 17.15.4c; affected 17.9.9; affected 17.12.5d; affected 16.12.15; affected 17.15.4s1; affected 17.15.5; affected 17.12.1z5; affected 17.18.1x; affected 17.12.1z6; affected 17.15.4d; affected 17.12.6b; affected 17.4.1c; affected 3.11.14E; affected 17.15.5a; affected 17.18.1y; affected 17.12.7a; affected 17.18.3; affected 17.12.7b; affected 17.18.3a; affected 26.1.1a; affected 26.2.1ea; affected 16.12.16

Cisco / IOS

affected 15.2(7)E7; affected 15.2(8)E3; affected 15.7(3)M10; affected 15.8(3)M9; affected 15.9(3)M7; affected 15.2(7)E8; affected 15.2(8)E4; affected 15.9(3)M7a; affected 15.2(2)E10c; affected 15.2(4)E10d; affected 15.9(3)M6a; affected 15.9(3)M6b; affected 15.5(1)SY10; affected 15.5(1)SY11; affected 15.2(6)E1a; affected 15.4(1)SY4; affected 15.5(1)SY1; affected 15.2(2)E8; affected 15.2(6)E1; affected 15.7(3)M2; affected 15.2(4)E6; affected 15.2(1)SY6; affected 15.2(4)EA7; affected 15.2(6)E1s; affected 15.7(3)M3; affected 15.8(3)M; affected 15.2(1)SY7; affected 15.2(4)EA8; affected 15.8(3)M0a; affected 15.2(2)E9; affected 15.2(6)E2; affected 15.5(1)SY2; affected 15.2(4)E7; affected 15.2(6)E2a; affected 15.2(2)E9a; affected 15.8(3)M0b; affected 15.2(6)E2b; affected 15.8(3)M1; affected 15.8(3)M1a; affected 15.7(3)M4; affected 15.2(1)SY8; affected 15.2(4)E8; affected 15.5(1)SY3; affected 15.2(7)E; affected 15.7(3)M4a; affected 15.8(3)M2; affected 15.2(7)E0a; affected 15.8(3)M2a; affected 15.7(3)M4b; affected 15.2(2)E10; affected 15.2(7)E0s; affected 15.2(4)EA9; affected 15.2(7)E0b; affected 15.2(6)E3; affected 15.9(3)M; affected 15.8(3)M3; affected 15.5(1)SY4; affected 15.7(3)M5; affected 15.2(2)E10a; affected 15.2(4)E9; affected 15.2(7)E1; affected 15.8(3)M3b; affected 15.9(3)M0a; affected 15.2(7)E1a; affected 15.2(4)E10; affected 15.5(1)SY5; affected 15.2(4)EA9a; affected 15.9(3)M1; affected 15.8(3)M4; affected 15.7(3)M6; affected 15.2(7)E2; affected 15.5(1)SY6; affected 15.2(7)E3; affected 15.8(3)M5; affected 15.7(3)M7; affected 15.9(3)M2; affected 15.2(7)E2b; affected 15.9(3)M2a; affected 15.2(4)E10a; affected 15.2(7)E4; affected 15.5(1)SY7; affected 15.2(4)E10b; affected 15.2(7)E3k; affected 15.2(8)E; affected 15.9(3)M3; affected 15.8(3)M6; affected 15.7(3)M8; affected 15.8(3)M7; affected 15.5(1)SY8; affected 15.2(7)E5; affected 15.2(8)E1; affected 15.9(3)M4; affected 15.2(8)E2; affected 15.2(4)E10c; affected 15.7(3)M9; affected 15.2(2)E10b; affected 15.2(7)E6; affected 15.9(3)M4a; affected 15.5(1)SY9; affected 15.9(3)M5; affected 15.8(3)M8; affected 15.9(3)M6; affected 15.9(3)M9; affected 15.5(1)SY13; affected 15.9(3)M8b; affected 15.2(7)E9; affected 15.5(1)SY12; affected 15.7(3)M10a; affected 15.9(3)M8; affected 15.9(3)M8a; affected 15.2(8)E5; affected 15.2(7)E10; affected 15.7(3)M10b; affected 15.9(3)M3a; affected 15.8(3)M3a; affected 15.9(3)M3b; affected 15.6(2)SP7; affected 15.6(2)SP5; affected 15.6(2)SP8; affected 15.6(2)SP6; affected 15.6(2)SP4; affected 15.6(2)SP9; affected 15.6(2)SP8a; affected 15.9(3)M9a; affected 15.2(8)E6; affected 15.9(3)M10; affected 15.2(7)E11; affected 15.5(1)SY14; affected 15.2(8)E7; affected 15.2(4)E10e; affected 15.9(3)M11; affected 15.2(7)E12; affected 15.5(1)SY15; affected 15.2(8)E8; affected 15.5(1)SY16; affected 15.2(7)E13; affected 15.9(3)M12; affected 15.5(1)SY17; affected 15.2(7)E14; affected 15.9(3)M13

CWE

CWE-606

References

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

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.