CVE-2021-34699 Cisco IOS and IOS XE Software TrustSec CLI Parser Denial of Service Vulnerability

High 7.7 Published 23 Sep 2021 Updated 18 Nov 2024

An authenticated remote attacker can cause a Cisco IOS device to reload by requesting a specific CLI command via the web UI, resulting in a denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-34699?

CVE-2021-34699 is a high-severity denial of service vulnerability in Cisco Ios, published on 23 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A vulnerability in the TrustSec CLI parser of Cisco IOS and Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload. This vulnerability is due to an improper interaction between the web UI and the CLI parser. An attacker could exploit this vulnerability by requesting a particular CLI command to be run through the web UI. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

Weakness: CWE-436, CWE-435

Which versions are affected by CVE-2021-34699?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2021-34699?

No fix has been published for CVE-2021-34699 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-34699 being exploited?

There is no known exploitation of CVE-2021-34699 in the wild and no public exploit code.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-6q78-w5mw-hqpj.