Is CVE-2021-34699 being actively exploited?

CVE-2021-34699 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2021-34699?

CVE-2021-34699 has a CVSS 3.1 base score of 7.7 (HIGH).

CVE-2021-34699

HIGH · CVSS 7.7EPSS 1.2%EU EUVD

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.

Key facts

CVSS score: 7.7 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Weakness (CWE): CWE-435
EPSS score: 1.2% (67th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2021-21349)
Published: September 23, 2021
NVD last modified: June 17, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-21349 in the EU Vulnerability Database. Last updated in EUVD on November 18, 2024.

View on the EU Vulnerability Database

Affected products

cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios
cisco / ios

and 784 more…

Certified products that may be affected

6 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Cisco Catalyst 3K/4K Wired Access Switches running IOS-XE 3.8.0E - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10688-2016 - archived
Cisco Aggregation Services Router (ASR) 1000 Series, IOS XE 3.13 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10609-2015 - archived
Cisco Integrated Services Router 4400 Series (ISR-4400), IOS XE 3.13.0 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10600-2015 - archived
Cisco Catalyst 3850 Series Switches running IOS-XE 3.6.0E and Catalyst 6500 Series Switches running IOS 15.1(2)SY3 - Cisco Systems, Inc. - Common Criteria NSCIB-CC-14-39582-CR - archived
Cisco Integrated Services Routers Series (ISR-4400), IOS XE 3.10.2tS - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10553-2014 - archived

See all 6 in the Security Certifications Explorer.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-trustsec-dos-7fuXDR2(Vendor Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

Query CVEs from your AI assistant

The CVE/NVD Explorer brain answers CVE questions directly inside Claude, ChatGPT, or any MCP assistant — always up to date, no setup. Add it once and stop pasting advisories into chat.

Add the CVE brain