Cisco · IOS XR
CVE-2020-3118
Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability
What it is
A vulnerability in the Cisco Discovery Protocol implementation for Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a reload on an affected device. The vulnerability is due to improper validation of string input from certain fields in Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges on an affected device. Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).
CISA: Cisco IOS XR improperly validates string input from certain fields in Cisco Discovery Protocol messages. Exploitation could allow an unauthenticated, adjacent attacker to execute code with administrative privileges or cause a reload on an affected device.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: May 3, 2022
More exploited flaws from Cisco
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| May 23, 2022 | Open Port | IOS XR | Medium 6.5 | 11% |
| Mar 25, 2022 | Border Gateway Protocol (BGP) Denial-of-Service | IOS XR | Medium 5.9 | 3.3% |
| Mar 25, 2022 | Border Gateway Protocol (BGP) Denial-of-Service | IOS XR | High 7.5 | 5.7% |
| Nov 3, 2021 | Software DVMRP Memory Exhaustion | IOS XR | High 8.6 | 3.7% |
| Nov 3, 2021 | Software DVMRP Memory Exhaustion | IOS XR | High 8.6 | 3.3% |
| Oct 14, 2026 | Relative Path Traversal | Secure Email Gateway | Critical 9.8 | 2.2% |
| Sep 30, 2026 | Hex Encoding | Catalyst SD-WAN Manager | Critical 9.8 | 39% |
| Sep 16, 2026 | Incorrect Use of Privileged APIs | Identity Services Engine | Critical 10.0 | 76% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.