IOS vulnerability

What happened

A vulnerability in the implementation of the TACACS+ protocol in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to view sensitive data or bypass authentication. This vulnerability exists because the system does not properly check whether the required TACACS+ shared secret is configured. A machine-in-the-middle attacker could exploit this vulnerability by intercepting and reading unencrypted TACACS+ messages or impersonating the TACACS+ server and falsely accepting arbitrary authentication requests. A successful exploit could allow the attacker to view sensitive information in a TACACS+ message or bypass authentication and gain access to the affected device.

Affected versions

IOS: 15.2(6)E1; 15.2(4)E6; 15.2(6)E2; 15.2(4)E7; 15.2(7)E; 15.2(4)E8; 15.2(6)E2a; 15.2(6)E2b; 15.2(7)E1; 15.2(7)E0a; 15.2(7)E0b; 15.2(7)E0s; 15.2(6)E3; 15.2(4)E9; 15.2(7)E2; 15.2(7a)E0b; 15.2(4)E10; 15.2(7)E3; 15.2(7)E1a; 15.2(7b)E0b; 15.2(7)E2a; 15.2(4)E10a; 15.2(7)E4; 15.2(7)E3k; 15.2(8)E; 15.2(8)E1; 15.2(7)E5; 15.2(7)E6; 15.2(8)E2; 15.2(4)E10d; 15.2(7)E7; 15.2(8)E3; 15.2(7)E8; 15.2(8)E4; 15.2(7)E9; 15.2(8)E5; 15.2(8)E6; 15.2(7)E10; 15.2(7)E11; 15.2(8)E7; 15.2(7)E12; 15.5(3)S8; 15.5(3)S9; 15.5(3)S10; 15.5(3)S9a; 15.2(6)EB; 15.5(3)M7; 15.5(3)M8; 15.5(3)M9; 15.5(3)M10; 15.6(2)SP5; 15.6(2)SP6; 15.6(2)SP7; 15.6(2)SP8; 15.6(2)SP9; 15.6(3)M4; 15.6(3)M5; 15.6(3)M6; 15.6(3)M7; 15.6(3)M6a; 15.6(3)M6b; 15.6(3)M8; 15.6(3)M9; 15.5(1)SY2; 15.5(1)SY3; 15.5(1)SY4; 15.5(1)SY5; 15.5(1)SY6; 15.5(1)SY7; 15.5(1)SY8; 15.5(1)SY9; 15.5(1)SY10; 15.5(1)SY11; 15.5(1)SY12; 15.5(1)SY13; 15.5(1)SY14; 15.5(1)SY15; 15.7(3)M3; 15.7(3)M2; 15.7(3)M4; 15.7(3)M5; 15.7(3)M4a; 15.7(3)M4b; 15.7(3)M6; 15.7(3)M7; 15.7(3)M8; 15.7(3)M9; 15.8(3)M; 15.8(3)M1; 15.8(3)M0a; 15.8(3)M0b; 15.8(3)M2; 15.8(3)M1a; 15.8(3)M3; 15.8(3)M2a; 15.8(3)M4; 15.8(3)M3a; 15.8(3)M3b; 15.8(3)M5; 15.8(3)M6; 15.8(3)M7; 15.8(3)M8; 15.8(3)M9; 15.9(3)M; 15.9(3)M1; 15.9(3)M0a; 15.9(3)M2; 15.9(3)M3; 15.9(3)M2a; 15.9(3)M3a; 15.9(3)M4; 15.9(3)M3b; 15.9(3)M5; 15.9(3)M4a; 15.9(3)M6; 15.9(3)M7; 15.9(3)M6a; 15.9(3)M6b; 15.9(3)M8; 15.9(3)M7a; 15.9(3)M9; 15.9(3)M8b; 15.9(3)M10; 15.9(3)M11; 3.16.8S; 3.16.9S; 3.16.10S; 3.8.6E; 3.8.7E; 3.8.8E; 3.8.9E; 3.8.10E; 3.18.5SP; 3.18.6SP; 3.18.7SP; 3.18.8aSP; 3.18.9SP; 16.6.5; 16.6.5a; 16.6.6; 16.6.7; 16.6.8; 16.6.9; 16.6.10; 16.8.1; 16.8.1a; 16.8.1b; 16.8.1s; 16.8.1c; 16.8.1d; 16.8.2; 16.8.1e; 16.8.3; 16.9.1; 16.9.2; 16.9.1a; 16.9.1b; 16.9.1s; 16.9.3; 16.9.4; 16.9.3a; 16.9.5; 16.9.5f; 16.9.6; 16.9.7; 16.9.8; 16.10.1; 16.10.1a; 16.10.1b; 16.10.1s; 16.10.1c; 16.10.1e; 16.10.1d; 16.10.2; 16.10.1f; 16.10.1g; 16.10.3; 3.10.1E; 3.10.2E; 3.10.3E; 16.11.1; 16.11.1a; 16.11.1b; 16.11.2; 16.11.1s; 16.12.1; 16.12.1s; 16.12.1a; 16.12.1c; 16.12.1w; 16.12.2; 16.12.1y; 16.12.2a; 16.12.3; 16.12.8; 16.12.2s; 16.12.1x; 16.12.1t; 16.12.4; 16.12.3s; 16.12.3a; 16.12.4a; 16.12.5; 16.12.6; 16.12.1z1; 16.12.5a; 16.12.5b; 16.12.1z2; 16.12.6a; 16.12.7; 16.12.9; 16.12.10; 16.12.10a; 16.12.11; 16.12.12; 16.12.13; 3.11.0E; 3.11.1E; 3.11.2E; 3.11.3E; 3.11.1aE; 3.11.4E; 3.11.3aE; 3.11.5E; 3.11.6E; 3.11.7E; 3.11.8E; 3.11.9E; 3.11.10E; 3.11.11E; 3.11.12E; 17.1.1; 17.1.1a; 17.1.1s; 17.1.1t; 17.1.3; 17.2.1; 17.2.1r; 17.2.1a; 17.2.1v; 17.2.2; 17.2.3; 17.3.1; 17.3.2; 17.3.3; 17.3.1a; 17.3.1w; 17.3.2a; 17.3.1x; 17.3.1z; 17.3.4; 17.3.5; 17.3.4a; 17.3.6; 17.3.4b; 17.3.4c; 17.3.5a; 17.3.5b; 17.3.7; 17.3.8; 17.3.8a; 17.4.1; 17.4.2; 17.4.1a; 17.4.1b; 17.4.2a; 17.5.1; 17.5.1a; 17.6.1; 17.6.2; 17.6.1w; 17.6.1a; 17.6.1x; 17.6.3; 17.6.1y; 17.6.1z; 17.6.3a; 17.6.4; 17.6.1z1; 17.6.5; 17.6.6; 17.6.6a; 17.6.5a; 17.6.7; 17.6.8; 17.6.8a; 17.7.1; 17.7.1a; 17.7.1b; 17.7.2; 17.10.1; 17.10.1a; 17.10.1b; 17.8.1; 17.8.1a; 17.9.1; 17.9.1w; 17.9.2; 17.9.1a; 17.9.1x; 17.9.1y; 17.9.3; 17.9.2a; 17.9.1x1; 17.9.3a; 17.9.4; 17.9.1y1; 17.9.5; 17.9.4a; 17.9.5a; 17.9.5b; 17.9.6; 17.9.6a; 17.9.7; 17.9.5e; 17.9.5f; 17.9.7a; 17.9.7b; 17.11.1; 17.11.1a; 17.12.1; 17.12.1w; 17.12.1a; 17.12.1x; 17.12.2; 17.12.3; 17.12.2a; 17.12.1y; 17.12.1z; 17.12.4; 17.12.3a; 17.12.1z1; 17.12.1z2; 17.12.4a; 17.12.5; 17.12.4b; 17.12.1z3; 17.12.5a; 17.12.1z4; 17.12.5b; 17.12.5c; 17.13.1; 17.13.1a; 17.14.1; 17.14.1a; 17.11.99SW; 17.15.1; 17.15.1w; 17.15.1a; 17.15.2; 17.15.1b; 17.15.1x; 17.15.3; 17.15.2c; 17.15.2a; 17.15.1y; 17.15.2b; 17.15.3a; 17.15.3b Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.