Cisco IOS XE ROM Monitor Software Vulnerability

published 2020-09-24 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-24795

cvss: 6.4; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits: 0; none known

A vulnerability in the Cisco IOS XE ROM Monitor (ROMMON) Software for Cisco 4000 Series Integrated Services Routers, Cisco ASR 920 Series Aggregation Services Routers, Cisco ASR 1000 Series Aggregation Services Routers, and Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, physical attacker to break the chain of trust and load a compromised software image on an affected device. The vulnerability is due to the presence of a debugging configuration option in the affected software. An attacker could exploit this vulnerability by connecting to an affected device through the console, forcing the device into ROMMON mode, and writing a malicious pattern using that specific option on the device. A successful exploit could allow the attacker to break the chain of trust and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.

Patch / fix

fixed in 1

cisco ios_xe_rom_monitor 15.6\(18r\), 16.2\(1r\), 16.4\(1r\)s

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 23 mo ago (2024-11-13)

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	6.4	CVSS:3.0/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	6.8	CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.9	AV:L/AC:M/Au:N/C:C/I:C/A:C

Affected products

Cisco Cisco IOS XE ROMMON Software

Classification

Weakness

CWE-284 Improper Access Control
CWE-862 Missing Authorization

References

tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-rommon-secboot-7JgVLVYC
vendor-advisory

Sources

CVE List CVE-2020-3524
NVD CVE-2020-3524

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary