CVE-2021-1435

—

CVSS 3.1

7.2 high

EPSS

8%p94

Published

Mar 24, 2021 (Mar 24, 2021)

Modified

Jun 17, 2026

Description

A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to inject arbitrary commands that can be executed as the root user. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted request to the web UI of an affected device with arbitrary commands injected into a portion of the request. A successful exploit could allow the attacker to execute arbitrary commands as the root user.

Vendors: cisco
Products: ios xe
Weakness: CWE-22
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

NVD CVE.org GitHub PoCs EPSS (8.1%)

In the news9 stories

"Disappearing" implants, followed by first fixes for exploited Cisco IOS XE zero-day

Help Net SecurityOct 31, 10:29 UTC · Oct 31, 2023Exploit / PoC CVE-2023-20198 CVE-2023-20273 CVE-2021-1435

Cisco IOS XE zero-day exploited by attackers to deliver implant (CVE-2023-20198)

Help Net SecurityOct 31, 10:28 UTC · Oct 31, 2023Exploit / PoC CVE-2023-20198 CVE-2021-1435

CISA adds Cisco IOS XE flaw to its Known Exploited Vulnerabilities catalog

Security AffairsOct 23, 19:49 UTC · Oct 23, 2023Exploit / PoC in the wildCVE-2021-1435 CVE-2023-20198

Cisco Zero-Day Exploited to Implant Malicious Lua Backdoor on Thousands of Devices

The Hacker NewsOct 23, 04:33 UTC · Oct 23, 2023Exploit / PoC in the wildCVE-2023-20273 CVE-2023-20198 CVE-2021-1435

Active exploitation of Cisco IOS XE Software Web Management User Interface vulnerabilities

Cisco TalosOct 16, 15:05 UTC · Oct 16, 2023Vulnerability in the wildCVE-2023-20198 CVE-2023-20273 CVE-2021-1435