Vulnerability Monitor

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CVE-2009-0635

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.

Security Impact Summary

CVE-2009-0635 is a security vulnerability that . Impacting 1 product from cisco organizations running these solutions should prioritize assessment and patching.

Historical Context

Originally identified in 2009, this vulnerability predates many modern security frameworks and practices. The vulnerability landscape of that era was characterized by different threat models and less mature defense mechanisms compared to contemporary standards.

Published

2009-03-27T16:30:02.077

Last Modified

2025-04-09T00:30:58.490

Status

Deferred

Source

[email protected]

Severity

CVSSv2: 7.1 (HIGH)

CVSSv2 Vector

AV:N/AC:M/Au:N/C:N/I:N/A:C

Access Vector: NETWORK
Access Complexity: MEDIUM
Authentication: NONE
Confidentiality Impact: NONE
Integrity Impact: NONE
Availability Impact: COMPLETE

Exploitability Score

8.6

Impact Score

6.9

Weaknesses

Type: Primary
CWE-399

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Operating System	cisco	ios	12.4t	Yes
Operating System	cisco	ios	12.4xz	Yes
Operating System	cisco	ios	12.4ya	Yes

References

http://secunia.com/advisories/34438 Vendor Advisory ([email protected])
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90459.shtml Patch, Vendor Advisory ([email protected])
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90469.shtml Patch, Vendor Advisory ([email protected])
http://www.securityfocus.com/bid/34246 ([email protected])
http://www.securitytracker.com/id?1021895 ([email protected])
http://www.vupen.com/english/advisories/2009/0851 Vendor Advisory ([email protected])
https://exchange.xforce.ibmcloud.com/vulnerabilities/49417 ([email protected])
http://secunia.com/advisories/34438 Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90459.shtml Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90469.shtml Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.securityfocus.com/bid/34246 (af854a3a-2127-422b-91ae-364da2661108)
http://www.securitytracker.com/id?1021895 (af854a3a-2127-422b-91ae-364da2661108)
http://www.vupen.com/english/advisories/2009/0851 Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://exchange.xforce.ibmcloud.com/vulnerabilities/49417 (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For cisco's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.