Is CVE-2021-1620 being actively exploited?

CVE-2021-1620 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2021-1620?

CVE-2021-1620 has a CVSS 3.1 base score of 7.7 (HIGH).

CVE-2021-1620

HIGH · CVSS 7.7EPSS 1.1%EU EUVD

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) support for the AutoReconnect feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to exhaust the free IP addresses from the assigned local pool. This vulnerability occurs because the code does not release the allocated IP address under certain failure conditions. An attacker could exploit this vulnerability by trying to connect to the device with a non-AnyConnect client. A successful exploit could allow the attacker to exhaust the IP addresses from the assigned local pool, which prevents users from logging in and leads to 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-563
EPSS score: 1.1% (64th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2021-7087)
Published: September 23, 2021
NVD last modified: June 17, 2026
Status: Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-7087 in the EU Vulnerability Database. Last updated in EUVD on November 7, 2024.

View on the EU Vulnerability Database

Affected products

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and 639 more…

Certified products that may be affected

4 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 Integrated Services Routers Series (ISR-4400), IOS XE 3.10.2tS - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10553-2014 - archived

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ikev2-ebFrwMPr(Patch, Vendor Advisory)

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

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