CVE-2009-0635: High severity Cisco IOS vulnerability
Memory leak in the Cisco Tunneling Control Protocol (cTCP) encapsulation feature in Cisco IOS 12.4, when an Easy VPN (aka EZVPN) server is enabled, allows remote attackers to cause a denial of service (memory consumption and device crash) via a sequence of TCP packets.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Disable the Cisco Tunneling Control Protocol (cTCP) encapsulation feature to prevent the memory leak that can lead to memory consumption and device crash.
Cisco IOS (cTCP encapsulation feature) cTCP encapsulation = disabled - Configuration
Disable the Easy VPN (EZVPN) server on affected devices; the vulnerability occurs when an EZVPN server is enabled.
Cisco IOS (Easy VPN / EZVPN server) Easy VPN (EZVPN) server = disabled
Event History
Frequently Asked Questions
What is the severity of CVE-2009-0635?
CVE-2009-0635 is considered a high severity vulnerability as it can lead to denial of service due to memory exhaustion.
How do I fix CVE-2009-0635?
To fix CVE-2009-0635, upgrade to a patched version of Cisco IOS that is not affected by this memory leak.
Which Cisco IOS versions are affected by CVE-2009-0635?
CVE-2009-0635 affects Cisco IOS versions 12.4t, 12.4ya, and 12.4xz.
Can CVE-2009-0635 be exploited remotely?
Yes, CVE-2009-0635 can be exploited remotely through a sequence of specially crafted TCP packets.
What are the consequences of an attack exploiting CVE-2009-0635?
Exploiting CVE-2009-0635 can lead to device crashes and service interruptions due to memory consumption.