Symptom

A vulnerability in the implementation of Border Gateway Protocol (BGP) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to incorrect processing of certain BGP update messages. An attacker could exploit this vulnerability by sending BGP update messages that include a specific set of attributes to be processed by an affected system. A successful exploit could allow the attacker to cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic from explicitly defined peers only. To exploit this vulnerability, the malicious BGP update message would need to come from a configured, valid BGP peer or would need to be injected by the attacker into the victim''s BGP network on an existing, valid TCP connection to a BGP peer. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190703-iosxr-bgp-dos

Conditions

Please refer to the Security Advisory. This affects all versions of Cisco IOS XR (Since 4.3.1) First Fixed Software: 6.6.2 7.0.1 SMUs Available: 4.3.2: XR12000: AA15835 5.3.3: ASR9K-PX: AA15882 5.3.4: ASR9K-PX: AA15857 6.1.3: ASR9K-PX: AA15813 6.1.4: CRS-PX: AA15854 6.1.4: ASR9K-PX: AA15855 6.2.2: CRS-PX: AA15809 6.2.3: ASR9K-PX: AA15810 6.3.3: ASR9K-X64: AA15853 6.4.2: ASR9K: AA15449 6.4.2: CRS-PX: AA15883 6.5.3: ASR9K: AA15448 6.5.3: ASR9K-X64: AA15812 6.5.3: NCS5500: AA15821

Workaround

None

Further Problem Description

PSIRT Evaluation

The Cisco PSIRT has assigned this bug the following CVSS version 3 score. The Base CVSS score as of the time of evaluation is 6.8: https://tools.cisco.com/security/center/cvssCalculator.x?version=3.0&vector=CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H CVE ID CVE-2019-1909 has been assigned to document this issue. Additional information on Cisco''s security vulnerability policy can be found at the following URL: http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html