Symptom
A vulnerability in the PPP over Ethernet (PPPoE) termination feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, adjacent attacker to crash the ppp_ma process, resulting in a denial of service (DoS) condition.
This vulnerability is due to the improper handling of malformed PPPoE packets that are received on a router that is running Broadband Network Gateway (BNG) functionality with PPPoE termination on a Lightspeed-based or Lightspeed-Plus-based line card. An attacker could exploit this vulnerability by sending a crafted PPPoE packet to an affected line card interface that does not terminate PPPoE. A successful exploit could allow the attacker to crash the ppp_ma process, resulting in a DoS condition for PPPoE traffic across the router.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-pppma-JKWFgneW
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
Conditions
Please refer to the Security Advisory.
Workaround
Please refer to the Security Advisory.
Further Problem Description
Please refer to the Security Advisory.
*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 7.4:
https://sec.cloudapps.cisco.com/security/center/cvssCalculator.x?vector=CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CVE ID CVE-2024-20327 has been assigned to document this issue.
Additional information on Cisco's security vulnerability policy can be found at the following URL:
https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html
