Are you still using telnet on Cisco devices? I think you should disable it!

The vulnerability is still unpatched


Cisco has published an advisory concerning a vulnerability in its product, discovered while analyzing the “Vault 7” documentation published by Wikileaks last week.

The vulnerability affects the Cluster Management Protocol in Cisco IOS and Cisco IOS XE Software and if exploited could allow a remote attacker to remotely execute malicious code on device with elevated privileges, bypassing the authentication:

An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device.


Affected Products

This vulnerability affects the following Cisco devices when running a vulnerable Cisco IOS software release and configured to accept incoming Telnet connections:

  • Cisco Catalyst 2350–48TD-S Switch
  • Cisco Catalyst 2350–48TD-SD Switch
  • Cisco Catalyst 2360–48TD-S Switch
  • Cisco Catalyst 2918–24TC-C Switch
  • Cisco Catalyst 2918–24TT-C Switch
  • Cisco Catalyst 2918–48TC-C Switch
  • Cisco Catalyst 2918–48TT-C Switch
  • Cisco Catalyst 2928–24TC-C Switch
  • Cisco Catalyst 2960–24-S Switch
  • Cisco Catalyst 2960–24LC-S Switch
  • Cisco Catalyst 2960–24LT-L Switch
  • Cisco Catalyst 2960–24PC-L Switch
  • Cisco Catalyst 2960–24PC-S Switch
  • Cisco Catalyst 2960–24TC-L Switch
  • Cisco Catalyst 2960–24TC-S Switch
  • Cisco Catalyst 2960–24TT-L Switch
  • Cisco Catalyst 2960–48PST-L Switch
  • Cisco Catalyst 2960–48PST-S Switch
  • Cisco Catalyst 2960–48TC-L Switch
  • Cisco Catalyst 2960–48TC-S Switch
  • Cisco Catalyst 2960–48TT-L Switch
  • Cisco Catalyst 2960–48TT-S Switch
  • Cisco Catalyst 2960–8TC-L Compact Switch
  • Cisco Catalyst 2960–8TC-S Compact Switch
  • Cisco Catalyst 2960-Plus 24LC-L Switch
  • Cisco Catalyst 2960-Plus 24LC-S Switch
  • Cisco Catalyst 2960-Plus 24PC-L Switch
  • Cisco Catalyst 2960-Plus 24PC-S Switch
  • Cisco Catalyst 2960-Plus 24TC-L Switch
  • Cisco Catalyst 2960-Plus 24TC-S Switch
  • Cisco Catalyst 2960-Plus 48PST-L Switch
  • Cisco Catalyst 2960-Plus 48PST-S Switch
  • Cisco Catalyst 2960-Plus 48TC-L Switch
  • Cisco Catalyst 2960-Plus 48TC-S Switch
  • Cisco Catalyst 2960C-12PC-L Switch
  • Cisco Catalyst 2960C-8PC-L Switch
  • Cisco Catalyst 2960C-8TC-L Switch
  • Cisco Catalyst 2960C-8TC-S Switch
  • Cisco Catalyst 2960CG-8TC-L Compact Switch
  • Cisco Catalyst 2960CPD-8PT-L Switch
  • Cisco Catalyst 2960CPD-8TT-L Switch
  • Cisco Catalyst 2960CX-8PC-L Switch
  • Cisco Catalyst 2960CX-8TC-L Switch
  • Cisco Catalyst 2960G-24TC-L Switch
  • Cisco Catalyst 2960G-48TC-L Switch
  • Cisco Catalyst 2960G-8TC-L Compact Switch
  • Cisco Catalyst 2960L-16PS-LL Switch
  • Cisco Catalyst 2960L-16TS-LL Switch
  • Cisco Catalyst 2960L-24PS-LL Switch
  • Cisco Catalyst 2960L-24TS-LL Switch
  • Cisco Catalyst 2960L-48PS-LL Switch
  • Cisco Catalyst 2960L-48TS-LL Switch
  • Cisco Catalyst 2960L-8PS-LL Switch
  • Cisco Catalyst 2960L-8TS-LL Switch
  • Cisco Catalyst 2960PD-8TT-L Compact Switch
  • Cisco Catalyst 2960S-24PD-L Switch
  • Cisco Catalyst 2960S-24PS-L Switch
  • Cisco Catalyst 2960S-24TD-L Switch
  • Cisco Catalyst 2960S-24TS-L Switch
  • Cisco Catalyst 2960S-24TS-S Switch
  • Cisco Catalyst 2960S-48FPD-L Switch
  • Cisco Catalyst 2960S-48FPS-L Switch
  • Cisco Catalyst 2960S-48LPD-L Switch
  • Cisco Catalyst 2960S-48LPS-L Switch
  • Cisco Catalyst 2960S-48TD-L Switch
  • Cisco Catalyst 2960S-48TS-L Switch
  • Cisco Catalyst 2960S-48TS-S Switch
  • Cisco Catalyst 2960S-F24PS-L Switch
  • Cisco Catalyst 2960S-F24TS-L Switch
  • Cisco Catalyst 2960S-F24TS-S Switch
  • Cisco Catalyst 2960S-F48FPS-L Switch
  • Cisco Catalyst 2960S-F48LPS-L Switch
  • Cisco Catalyst 2960S-F48TS-L Switch
  • Cisco Catalyst 2960S-F48TS-S Switch
  • Cisco Catalyst 2960X-24PD-L Switch
  • Cisco Catalyst 2960X-24PS-L Switch
  • Cisco Catalyst 2960X-24PSQ-L Cool Switch
  • Cisco Catalyst 2960X-24TD-L Switch
  • Cisco Catalyst 2960X-24TS-L Switch
  • Cisco Catalyst 2960X-24TS-LL Switch
  • Cisco Catalyst 2960X-48FPD-L Switch
  • Cisco Catalyst 2960X-48FPS-L Switch
  • Cisco Catalyst 2960X-48LPD-L Switch
  • Cisco Catalyst 2960X-48LPS-L Switch
  • Cisco Catalyst 2960X-48TD-L Switch
  • Cisco Catalyst 2960X-48TS-L Switch
  • Cisco Catalyst 2960X-48TS-LL Switch
  • Cisco Catalyst 2960XR-24PD-I Switch
  • Cisco Catalyst 2960XR-24PD-L Switch
  • Cisco Catalyst 2960XR-24PS-I Switch
  • Cisco Catalyst 2960XR-24PS-L Switch
  • Cisco Catalyst 2960XR-24TD-I Switch
  • Cisco Catalyst 2960XR-24TD-L Switch
  • Cisco Catalyst 2960XR-24TS-I Switch
  • Cisco Catalyst 2960XR-24TS-L Switch
  • Cisco Catalyst 2960XR-48FPD-I Switch
  • Cisco Catalyst 2960XR-48FPD-L Switch
  • Cisco Catalyst 2960XR-48FPS-I Switch
  • Cisco Catalyst 2960XR-48FPS-L Switch
  • Cisco Catalyst 2960XR-48LPD-I Switch
  • Cisco Catalyst 2960XR-48LPD-L Switch
  • Cisco Catalyst 2960XR-48LPS-I Switch
  • Cisco Catalyst 2960XR-48LPS-L Switch
  • Cisco Catalyst 2960XR-48TD-I Switch
  • Cisco Catalyst 2960XR-48TD-L Switch
  • Cisco Catalyst 2960XR-48TS-I Switch
  • Cisco Catalyst 2960XR-48TS-L Switch
  • Cisco Catalyst 2970G-24T Switch
  • Cisco Catalyst 2970G-24TS Switch
  • Cisco Catalyst 2975 Switch
  • Cisco Catalyst 3550 12G Switch
  • Cisco Catalyst 3550 12T Switch
  • Cisco Catalyst 3550 24 DC SMI Switch
  • Cisco Catalyst 3550 24 EMI Switch
  • Cisco Catalyst 3550 24 FX SMI Switch
  • Cisco Catalyst 3550 24 PWR Switch
  • Cisco Catalyst 3550 24 SMI Switch
  • Cisco Catalyst 3550 48 EMI Switch
  • Cisco Catalyst 3550 48 SMI Switch
  • Cisco Catalyst 3560–12PC-S Compact Switch
  • Cisco Catalyst 3560–24PS Switch
  • Cisco Catalyst 3560–24TS Switch
  • Cisco Catalyst 3560–48PS Switch
  • Cisco Catalyst 3560–48TS Switch
  • Cisco Catalyst 3560–8PC Compact Switch
  • Cisco Catalyst 3560C-12PC-S Switch
  • Cisco Catalyst 3560C-8PC-S Switch
  • Cisco Catalyst 3560CG-8PC-S Compact Switch
  • Cisco Catalyst 3560CG-8TC-S Compact Switch
  • Cisco Catalyst 3560CPD-8PT-S Compact Switch
  • Cisco Catalyst 3560CX-12PC-S Switch
  • Cisco Catalyst 3560CX-12PD-S Switch
  • Cisco Catalyst 3560CX-12TC-S Switch
  • Cisco Catalyst 3560CX-8PC-S Switch
  • Cisco Catalyst 3560CX-8PT-S Switch
  • Cisco Catalyst 3560CX-8TC-S Switch
  • Cisco Catalyst 3560CX-8XPD-S Switch
  • Cisco Catalyst 3560E-12D-E Switch
  • Cisco Catalyst 3560E-12D-S Switch
  • Cisco Catalyst 3560E-12SD-E Switch
  • Cisco Catalyst 3560E-12SD-S Switch
  • Cisco Catalyst 3560E-24PD-E Switch
  • Cisco Catalyst 3560E-24PD-S Switch
  • Cisco Catalyst 3560E-24TD-E Switch
  • Cisco Catalyst 3560E-24TD-S Switch
  • Cisco Catalyst 3560E-48PD-E Switch
  • Cisco Catalyst 3560E-48PD-EF Switch
  • Cisco Catalyst 3560E-48PD-S Switch
  • Cisco Catalyst 3560E-48PD-SF Switch
  • Cisco Catalyst 3560E-48TD-E Switch
  • Cisco Catalyst 3560E-48TD-S Switch
  • Cisco Catalyst 3560G-24PS Switch
  • Cisco Catalyst 3560G-24TS Switch
  • Cisco Catalyst 3560G-48PS Switch
  • Cisco Catalyst 3560G-48TS Switch
  • Cisco Catalyst 3560V2–24DC Switch
  • Cisco Catalyst 3560V2–24PS Switch
  • Cisco Catalyst 3560V2–24TS Switch
  • Cisco Catalyst 3560V2–48PS Switch
  • Cisco Catalyst 3560V2–48TS Switch
  • Cisco Catalyst 3560X-24P-E Switch
  • Cisco Catalyst 3560X-24P-L Switch
  • Cisco Catalyst 3560X-24P-S Switch
  • Cisco Catalyst 3560X-24T-E Switch
  • Cisco Catalyst 3560X-24T-L Switch
  • Cisco Catalyst 3560X-24T-S Switch
  • Cisco Catalyst 3560X-24U-E Switch
  • Cisco Catalyst 3560X-24U-L Switch
  • Cisco Catalyst 3560X-24U-S Switch
  • Cisco Catalyst 3560X-48P-E Switch
  • Cisco Catalyst 3560X-48P-L Switch
  • Cisco Catalyst 3560X-48P-S Switch
  • Cisco Catalyst 3560X-48PF-E Switch
  • Cisco Catalyst 3560X-48PF-L Switch
  • Cisco Catalyst 3560X-48PF-S Switch
  • Cisco Catalyst 3560X-48T-E Switch
  • Cisco Catalyst 3560X-48T-L Switch
  • Cisco Catalyst 3560X-48T-S Switch
  • Cisco Catalyst 3560X-48U-E Switch
  • Cisco Catalyst 3560X-48U-L Switch
  • Cisco Catalyst 3560X-48U-S Switch
  • Cisco Catalyst 3750 Metro 24-AC Switch
  • Cisco Catalyst 3750 Metro 24-DC Switch
  • Cisco Catalyst 3750–24FS Switch
  • Cisco Catalyst 3750–24PS Switch
  • Cisco Catalyst 3750–24TS Switch
  • Cisco Catalyst 3750–48PS Switch
  • Cisco Catalyst 3750–48TS Switch
  • Cisco Catalyst 3750E-24PD-E Switch
  • Cisco Catalyst 3750E-24PD-S Switch
  • Cisco Catalyst 3750E-24TD-E Switch
  • Cisco Catalyst 3750E-24TD-S Switch
  • Cisco Catalyst 3750E-48PD-E Switch
  • Cisco Catalyst 3750E-48PD-EF Switch
  • Cisco Catalyst 3750E-48PD-S Switch
  • Cisco Catalyst 3750E-48PD-SF Switch
  • Cisco Catalyst 3750E-48TD-E Switch
  • Cisco Catalyst 3750E-48TD-S Switch
  • Cisco Catalyst 3750G-12S Switch
  • Cisco Catalyst 3750G-12S-SD Switch
  • Cisco Catalyst 3750G-16TD Switch
  • Cisco Catalyst 3750G-24PS Switch
  • Cisco Catalyst 3750G-24T Switch
  • Cisco Catalyst 3750G-24TS Switch
  • Cisco Catalyst 3750G-24TS-1U Switch
  • Cisco Catalyst 3750G-48PS Switch
  • Cisco Catalyst 3750G-48TS Switch
  • Cisco Catalyst 3750V2–24FS Switch
  • Cisco Catalyst 3750V2–24PS Switch
  • Cisco Catalyst 3750V2–24TS Switch
  • Cisco Catalyst 3750V2–48PS Switch
  • Cisco Catalyst 3750V2–48TS Switch
  • Cisco Catalyst 3750X-12S-E Switch
  • Cisco Catalyst 3750X-12S-S Switch
  • Cisco Catalyst 3750X-24P-E Switch
  • Cisco Catalyst 3750X-24P-L Switch
  • Cisco Catalyst 3750X-24P-S Switch
  • Cisco Catalyst 3750X-24S-E Switch
  • Cisco Catalyst 3750X-24S-S Switch
  • Cisco Catalyst 3750X-24T-E Switch
  • Cisco Catalyst 3750X-24T-L Switch
  • Cisco Catalyst 3750X-24T-S Switch
  • Cisco Catalyst 3750X-24U-E Switch
  • Cisco Catalyst 3750X-24U-L Switch
  • Cisco Catalyst 3750X-24U-S Switch
  • Cisco Catalyst 3750X-48P-E Switch
  • Cisco Catalyst 3750X-48P-L Switch
  • Cisco Catalyst 3750X-48P-S Switch
  • Cisco Catalyst 3750X-48PF-E Switch
  • Cisco Catalyst 3750X-48PF-L Switch
  • Cisco Catalyst 3750X-48PF-S Switch
  • Cisco Catalyst 3750X-48T-E Switch
  • Cisco Catalyst 3750X-48T-L Switch
  • Cisco Catalyst 3750X-48T-S Switch
  • Cisco Catalyst 3750X-48U-E Switch
  • Cisco Catalyst 3750X-48U-L Switch
  • Cisco Catalyst 3750X-48U-S Switch
  • Cisco Catalyst 4000 Supervisor Engine I
  • Cisco Catalyst 4000/4500 Supervisor Engine IV
  • Cisco Catalyst 4000/4500 Supervisor Engine V
  • Cisco Catalyst 4500 Series Supervisor Engine II-Plus
  • Cisco Catalyst 4500 Series Supervisor Engine II-Plus-TS
  • Cisco Catalyst 4500 Series Supervisor Engine V-10GE
  • Cisco Catalyst 4500 Series Supervisor II-Plus-10GE
  • Cisco Catalyst 4500 Supervisor Engine 6-E
  • Cisco Catalyst 4500 Supervisor Engine 6L-E
  • Cisco Catalyst 4900M Switch
  • Cisco Catalyst 4928 10 Gigabit Ethernet Switch
  • Cisco Catalyst 4948 10 Gigabit Ethernet Switch
  • Cisco Catalyst 4948 Switch
  • Cisco Catalyst 4948E Ethernet Switch
  • Cisco Catalyst 4948E-F Ethernet Switch
  • Cisco Catalyst Blade Switch 3020 for HP
  • Cisco Catalyst Blade Switch 3030 for Dell
  • Cisco Catalyst Blade Switch 3032 for Dell M1000E
  • Cisco Catalyst Blade Switch 3040 for FSC
  • Cisco Catalyst Blade Switch 3120 for HP
  • Cisco Catalyst Blade Switch 3120X for HP
  • Cisco Catalyst Blade Switch 3130 for Dell M1000E
  • Cisco Catalyst C2928–24LT-C Switch
  • Cisco Catalyst C2928–48TC-C Switch
  • Cisco Catalyst Switch Module 3012 for IBM BladeCenter
  • Cisco Catalyst Switch Module 3110 for IBM BladeCenter
  • Cisco Catalyst Switch Module 3110X for IBM BladeCenter
  • Cisco Embedded Service 2020 24TC CON B Switch
  • Cisco Embedded Service 2020 24TC CON Switch
  • Cisco Embedded Service 2020 24TC NCP B Switch
  • Cisco Embedded Service 2020 24TC NCP Switch
  • Cisco Embedded Service 2020 CON B Switch
  • Cisco Embedded Service 2020 CON Switch
  • Cisco Embedded Service 2020 NCP B Switch
  • Cisco Embedded Service 2020 NCP Switch
  • Cisco Enhanced Layer 2 EtherSwitch Service Module
  • Cisco Enhanced Layer 2/3 EtherSwitch Service Module
  • Cisco Gigabit Ethernet Switch Module (CGESM) for HP
  • Cisco IE 2000–16PTC-G Industrial Ethernet Switch
  • Cisco IE 2000–16T67 Industrial Ethernet Switch
  • Cisco IE 2000–16T67P Industrial Ethernet Switch
  • Cisco IE 2000–16TC Industrial Ethernet Switch
  • Cisco IE 2000–16TC-G Industrial Ethernet Switch
  • Cisco IE 2000–16TC-G-E Industrial Ethernet Switch
  • Cisco IE 2000–16TC-G-N Industrial Ethernet Switch
  • Cisco IE 2000–16TC-G-X Industrial Ethernet Switch
  • Cisco IE 2000–24T67 Industrial Ethernet Switch
  • Cisco IE 2000–4S-TS-G Industrial Ethernet Switch
  • Cisco IE 2000–4T Industrial Ethernet Switch
  • Cisco IE 2000–4T-G Industrial Ethernet Switch
  • Cisco IE 2000–4TS Industrial Ethernet Switch
  • Cisco IE 2000–4TS-G Industrial Ethernet Switch
  • Cisco IE 2000–8T67 Industrial Ethernet Switch
  • Cisco IE 2000–8T67P Industrial Ethernet Switch
  • Cisco IE 2000–8TC Industrial Ethernet Switch
  • Cisco IE 2000–8TC-G Industrial Ethernet Switch
  • Cisco IE 2000–8TC-G-E Industrial Ethernet Switch
  • Cisco IE 2000–8TC-G-N Industrial Ethernet Switch
  • Cisco IE 3000–4TC Industrial Ethernet Switch
  • Cisco IE 3000–8TC Industrial Ethernet Switch
  • Cisco IE-3010–16S-8PC Industrial Ethernet Switch
  • Cisco IE-3010–24TC Industrial Ethernet Switch
  • Cisco IE-4000–16GT4G-E Industrial Ethernet Switch
  • Cisco IE-4000–16T4G-E Industrial Ethernet Switch
  • Cisco IE-4000–4GC4GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000–4GS8GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000–4S8P4G-E Industrial Ethernet Switch
  • Cisco IE-4000–4T4P4G-E Industrial Ethernet Switch
  • Cisco IE-4000–4TC4G-E Industrial Ethernet Switch
  • Cisco IE-4000–8GS4G-E Industrial Ethernet Switch
  • Cisco IE-4000–8GT4G-E Industrial Ethernet Switch
  • Cisco IE-4000–8GT8GP4G-E Industrial Ethernet Switch
  • Cisco IE-4000–8S4G-E Industrial Ethernet Switch
  • Cisco IE-4000–8T4G-E Industrial Ethernet Switch
  • Cisco IE-4010–16S12P Industrial Ethernet Switch
  • Cisco IE-4010–4S24P Industrial Ethernet Switch
  • Cisco IE-5000–12S12P-10G Industrial Ethernet Switch
  • Cisco IE-5000–16S12P Industrial Ethernet Switch
  • Cisco ME 4924–10GE Switch
  • Cisco RF Gateway 10
  • Cisco SM-X Layer 2/3 EtherSwitch Service Module

The fix is not yet available

Currently, this vulnerability is still unpatched, and until patches are available the vendor recommends to use SSH to remote management of devices and disable the telnet connection:

Cisco will release software updates that address this vulnerability. There are no workarounds that address this vulnerability.


More technical details

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp

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