CVE-2020-3118
HighExploitedPublic exploitA 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.
Published Feb 5, 2020 · Updated Oct 28, 2025
Key Facts
Patch immediately- CVE-2020-3118 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting IOS Xr (Cisco), Cisco IOS XR Software.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Oct 20, 2020. Public exploit code is available.
- EPSS estimates a 12% probability of exploitation in the next 30 days.
- Fixed versions are available, including IOS Xr 6.6.12, Cisco IOS XR Software 6.6.3.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
12%
Higher than 96.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
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).
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| Industry KEV feed | Oct 20, 2020 | May 3, 2022 | Not reported |
| CIRCL KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
7 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| IOS XrCisco | 5.2.5, 6.4.2, 6.5.3, 6.6.25, 7.0.1 | 6.6.12 |
| Cisco IOS XR Software | >= unspecified | 6.6.3 |
Patched Releases
IOS Xr
6.6.12
Cisco IOS XR Software
6.6.3
Timeline
Publicly disclosed
Feb 5, 2020
Added to Industry KEV feed
Oct 20, 2020
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Oct 28, 2025
Weakness Type
- CWE-134 Use of Externally-Controlled Format String
- CWE-787 Out-of-bounds Write
References
- advisoryhttp://packetstormsecurity.com/files/156203/Cisco-Discovery-Protocol-CDP-Remote-Device-Takeover.html
- advisory20200205 Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: IOS Xr (Cisco) versions 5.2.5, 6.4.2, 6.5.3, 6.6.25, 7.0.1; Cisco IOS XR Software versions >= unspecified. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Oct 20, 2020.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of May 3, 2022.
Public exploit code is available.
Fixed versions are available, including IOS Xr 6.6.12, Cisco IOS XR Software 6.6.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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