CVE-2010-2835: Cisco IOS

High severity, CVSS 7.8. EPSS: 1.8% chance of exploitation in the next 30 days.

Cisco IOS 12.2 through 12.4 and 15.0 through 15.1, Cisco IOS XE 2.5.x and 2.6.x before 2.6.1, and Cisco Unified Communications Manager (aka CUCM, formerly CallManager) 6.x before 6.1(5), 7.0 before 7.0(2a)su3, 7.1su before 7.1(3b)su2, 7.1 before 7.1(5), and 8.0 before 8.0(1) allow remote attackers to cause a denial of service (device reload or voice-services outage) via a SIP REFER request with an invalid Refer-To header, aka Bug IDs CSCta20040 and CSCta31358.

Affected products

• Cisco IOS: version 12.1 only; version 12.1t only; version 12.1xi only; version 12.1xj only; version 12.1xl only; version 12.1xm only; …
• Cisco IOS XE: version 2.5.0 only; version 2.5.1 only; version 2.6.0 only; version 2.6.1 only
• Cisco Unified Communications Manager: version 6.0 only; version 6.0(1.2114.1) only; version 6.0(1.2121.1) only; version 6.0(1b) only; version 6.1(1) only; version 6.1(1a) only; …

Published 2010-09-23. Last modified 2026-06-16.