CVE-2021-1620 json
Cisco IOS and IOS XE Software IKEv2 AutoReconnect Feature Denial of Service Vulnerability
published 2021-09-23 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7087
- cvss
- 7.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 65%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
1.07% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |
| NVD | 3.1 | 7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |
| NVD | 2.0 | 3.5 | AV:N/AC:M/Au:S/C:N/I:N/A:P |
Affected products
- Cisco Cisco IOS
Classification
- Weakness
- Technology feeds
References
-
tools.cisco.com
/security/center/content/CiscoSecurityAdvisory/cisco-sa-ikev2-ebFrwMPr
vendor-advisory, patch
Sources
- CVE List CVE-2021-1620
- NVD CVE-2021-1620
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