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Vulnerability record · CVE-2021-1435 · published 24 March 2021

CVE-2021-1435: Cisco ios xe path traversal vulnerability

Cisco · Ios Xe

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.

7.2 CVSS 3.1 High EPSS 8.1% · top 5.4% CWE-22 · Path traversal
7.2CVSS 3.1 base score, v2 9.0
8.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webcmdinjsh-UFJxTgZD Vendor Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webcmdinjsh-UFJxTgZD Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2023-20198Cisco IOS XE Web UI unauthenticated privilege escalation and implant deploymentCVE-2023-20198 is a critical flaw in the Cisco IOS XE web UI that lets an unauthenticated remote attacker gain initial access and create a local priv…KEVEPSS 100%analysed9.8CVE-2018-0151Cisco IOS/IOS XE QoS UDP Port 18999 Buffer OverflowCisco IOS and IOS XE contain a buffer overflow in the QoS subsystem caused by incorrect bounds checking of values in packets sent to UDP port 18999. …KEVEPSS 14%analysed9.8CVE-2017-3881Cisco IOS/IOS XE CMP Telnet Option Handling RCECisco IOS and IOS XE fail to restrict CMP-specific Telnet options to internal cluster communications and mishandle malformed CMP Telnet options, so a…KEVEPSS 99%analysed8.8CVE-2018-0167Cisco IOS, IOS XE and IOS XR LLDP buffer overflowMultiple buffer overflow flaws exist in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS, IOS XE and IOS XR Software. An unauthenticat…KEVEPSS 3.4%analysed8.8CVE-2017-6736Cisco IOS and IOS XE SNMP buffer overflow remote code executionThe SNMP subsystem in Cisco IOS and IOS XE contains a buffer overflow that can be triggered by a crafted SNMP packet sent over IPv4 or IPv6. It affec…KEVEPSS 70%analysed8.8CVE-2017-6737Cisco IOS and IOS XE SNMP Buffer Overflow RCECisco IOS and IOS XE contain a buffer overflow in the SNMP implementation that affects SNMPv1, v2c, and v3. An authenticated remote attacker who know…KEVEPSS 45%analysed8.8CVE-2017-6738Cisco IOS and IOS XE SNMP buffer overflow allows remote code executionThe SNMP subsystem in Cisco IOS and IOS XE Software contains a buffer overflow that affects SNMP versions 1, 2c, and 3. An authenticated remote attac…KEVEPSS 11%analysed8.8CVE-2017-6739Cisco IOS and IOS XE SNMP buffer overflow allows remote code executionCisco IOS and IOS XE contain a buffer overflow in the SNMP implementation that affects SNMP versions 1, 2c, and 3. A remote attacker who knows the SN…KEVEPSS 11%analysed

Source: NIST National Vulnerability Database (record CVE-2021-1435), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.