CVE-2026-20301
CVE CVE-2026-20301EUVD EUVD-2026-53467Published 2026-08-05T16:28:37.000ZLast changed 2026-08-05T17:45:13.000ZCVSS 8.6
What the advisory describes
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.
Source: EUVD (ENISA), in the words of the advisory.
Products the advisory names
These come from the advisory itself, not from any check we performed.
- Cisco — Cisco IOS XE Software 16.12.4; 17.12.5a; 3.11.5E; 17.9.4a; 17.15.5; 17.12.2a; 16.11.1a; 17.16.1; 17.9.1w; 16.12.10a; 17.12.5d; 16.12.16; 17.15.1y; 17.15.1a; 17.1.1; 17.12.1z3; 16.10.1c; 17.9.7b; 17.15.3; 17.10.1a; 16.7.2; 17.15.1x; 16.10.1e; 16.6.4s; 3.11.3E; 17.12.1x; 17.6.1z; 16.9.8; 17.9.5d; 17.15.3b; 17.9.5e; 17.18.1y; 17.6.5a; 16.12.1y; 17.12.6a; 17.6.6; 16.12.7; 17.6.3; 17.12.1z6; 16.12.2s; 3.18.9SP; 16.10.1s; 17.9.5f; 16.9.1s; 17.15.4; 17.6.8a; 17.12.4b; 16.12.14; 16.12.3a; 17.3.1a; 17.15.1b; 17.12.1z5; 16.9.3; 3.11.11E; 17.18.2; 16.8.1s; 16.8.1a; 16.9.2; 16.12.10; 17.6.8; 16.10.1a; 17.4.1c; 17.3.1w; 17.12.7; 17.12.4; 17.7.1b; 17.18.1; 17.15.1w; 17.1.1s; 16.9.1; 17.3.5; 17.15.2; 17.18.1a; 17.6.6a; 16.12.6; 16.6.5b; 17.6.1a; 16.8.1; 17.9.2; 17.1.2; 17.10.1; 17.4.1b; 16.12.1t; 17.6.1z1; 16.11.2; 16.7.1a; 3.11.3aE; 16.12.1x; 17.3.2a; 17.12.1y; 17.7.1; 16.8.1c; 17.12.1a; 17.9.5c; 17.12.1z4; 17.1.1a; 17.13.1; 16.12.2; 3.8.10dE; 16.6.3; 17.18.1x; 17.6.4; 17.6.1x; 17.9.2a; 17.12.2; 16.12.2t; 16.12.5; 17.12.4a; 17.3.4c; 17.9.6a; 16.12.1z; 16.7.1; 16.6.7; 16.8.1b; 17.11.1a; 17.3.6; 16.10.1b; 17.15.2b; 17.18.3; 16.11.1c; 3.11.9E; 17.9.3a; 17.3.4b; 17.14.1a; 17.9.6; 17.18.1w; 17.2.1v; 17.12.3; 16.12.6a; 17.12.1; 16.12.1s; 26.1.1; 16.10.2; 17.18.1z; 16.10.1; 16.12.1z1; 17.3.1; 16.12.3; 16.12.11; 3.16.10aS; 17.6.2; 3.11.13E; 17.9.1x1; 16.12.3s; 3.11.4E; 16.6.5; 16.6.5a; 16.9.1c; 17.16.1a; 17.4.2; 3.18.8aSP; 16.7.4; 17.9.1; 16.9.3s; 16.9.1a; 17.3.5b; 17.9.1y; 17.7.2; 17.9.1a; 17.3.5a; 16.6.2; 17.12.1z2; 17.13.1a; 17.15.4b; 17.1.1t; 17.12.6b; 16.9.3h; 16.10.1d; 16.6.7a; 17.14.1; 16.11.1; 3.16.10bS; 17.15.2a; 16.8.1e; 16.12.1w; 17.15.4s1; 17.9.4; 17.6.1; 17.12.5b; 16.6.8; 16.12.12; 16.9.6; 16.9.8a; 17.12.1z; 16.9.1d; 17.12.1w; 16.6.9; 17.2.2; 17.9.5a; 17.3.1x; 17.2.1; 16.9.7; 16.12.15; 17.2.1a; 17.15.5a; 17.9.3; 16.11.1s; 17.3.4a; 16.7.3; 16.12.8; 17.3.8a; 17.18.3a; 17.4.2a; 26.2.1ea; 17.9.5; 17.3.3; 16.8.1d; 16.12.4a; 17.6.3a; 3.11.7E; 17.15.4d; 16.9.8b; 17.8.1; 17.9.7a; 16.6.4a; 17.1.3; 17.3.1z; 16.10.1g; 17.3.2; 3.11.14E; 17.11.1; 16.6.4; 16.9.5; 3.8.10cE; 16.6.6; 16.8.3; 17.3.4; 17.15.1; 17.12.7b; 17.12.1z1; 17.9.1y1; 17.12.5c; 16.10.3; 17.12.5; 3.11.6E; 16.12.9; 17.6.5; 16.12.1z2; 17.9.7; 17.9.9; 17.15.3a; 17.3.8; 17.6.7; 17.15.2c; 16.12.2a; 16.7.1b; 17.12.3a; 17.9.1x; 17.5.1; 3.11.10E; 17.7.1a; 16.9.3a; 16.9.4; 3.11.8E; 16.12.5b; 16.6.10; 16.9.5f; 16.9.2s; 17.2.3; 17.12.6; 17.4.1a; 16.12.1; 16.12.1a; 17.12.7a; 17.15.4c; 16.11.1b; 16.9.2a; 17.2.1r; 3.11.12E; 17.3.7; 17.17.1; 17.15.4a; 16.9.4c; 16.8.2; 17.5.1a; 16.12.5a; 17.8.1a; 16.12.13; 17.3.3a; 16.10.1f; 17.9.8; 16.12.1c; 16.9.1b; 17.9.5b; 17.10.1b; 17.4.1; 26.1.1a
- Cisco — IOS 15.2(7)E11; 15.2(8)E; 15.2(7)E9; 15.8(3)M5; 15.9(3)M8; 15.2(7)E; 15.2(4)E10c; 15.5(1)SY7; 15.2(6)E2; 15.2(8)E8; 15.5(1)SY6; 15.8(3)M7; 15.7(3)M4a; 15.2(4)E9; 15.6(2)SP5; 15.9(3)M; 15.5(1)SY17; 15.2(2)E9a; 15.2(7)E13; 15.7(3)M10; 15.6(2)SP8a; 15.7(3)M8; 15.9(3)M2a; 15.8(3)M4; 15.8(3)M1a; 15.8(3)M3b; 15.9(3)M7a; 15.2(2)E8; 15.2(8)E5; 15.2(1)SY6; 15.2(7)E2b; 15.9(3)M13; 15.5(1)SY14; 15.2(7)E2; 15.2(8)E1; 15.2(7)E10; 15.5(1)SY3; 15.4(1)SY4; 15.9(3)M6a; 15.2(1)SY8; 15.2(2)E9; 15.2(4)E10; 15.9(3)M0a; 15.2(7)E3; 15.7(3)M2; 15.2(7)E8; 15.9(3)M9a; 15.8(3)M3; 15.8(3)M1; 15.5(1)SY16; 15.2(4)EA7; 15.7(3)M3; 15.2(7)E0b; 15.7(3)M4b; 15.5(1)SY13; 15.2(7)E3k; 15.9(3)M4a; 15.9(3)M6; 15.7(3)M5; 15.2(6)E2a; 15.2(7)E6; 15.7(3)M10b; 15.9(3)M11; 15.5(1)SY12; 15.2(8)E3; 15.9(3)M1; 15.9(3)M8b; 15.2(8)E4; 15.9(3)M3; 15.2(4)E7; 15.9(3)M12; 15.8(3)M3a; 15.9(3)M8a; 15.2(6)E1s; 15.7(3)M9; 15.8(3)M8; 15.2(1)SY7; 15.2(4)E10a; 15.2(7)E0a; 15.9(3)M3a; 15.2(2)E10; 15.6(2)SP9; 15.2(8)E6; 15.2(7)E1a; 15.8(3)M2; 15.9(3)M4; 15.7(3)M4; 15.5(1)SY5; 15.8(3)M; 15.5(1)SY9; 15.2(7)E4; 15.2(8)E2; 15.8(3)M9; 15.5(1)SY8; 15.8(3)M0b; 15.2(4)E10b; 15.2(6)E3; 15.2(4)EA9a; 15.7(3)M7; 15.5(1)SY10; 15.2(7)E14; 15.5(1)SY1; 15.9(3)M2; 15.2(6)E2b; 15.2(4)E10d; 15.2(2)E10a; 15.6(2)SP6; 15.6(2)SP7; 15.2(4)E10e; 15.9(3)M6b; 15.2(7)E0s; 15.2(7)E5; 15.5(1)SY15; 15.2(6)E1; 15.6(2)SP4; 15.6(2)SP8; 15.8(3)M0a; 15.9(3)M9; 15.2(8)E7; 15.7(3)M10a; 15.9(3)M10; 15.5(1)SY4; 15.2(2)E10b; 15.2(4)EA8; 15.9(3)M5; 15.8(3)M6; 15.7(3)M6; 15.5(1)SY11; 15.2(4)E8; 15.8(3)M2a; 15.2(7)E7; 15.5(1)SY2; 15.2(4)EA9; 15.9(3)M7; 15.2(7)E1; 15.2(6)E1a; 15.2(2)E10c; 15.2(4)E6; 15.9(3)M3b; 15.2(7)E12
The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.
Carried in the product catalogue
An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.
- Cisco — IOS Software
- Cisco — IOS XE Software
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