Known exploited vulnerability · CISA KEV

CVE-2023-20109: Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Vulnerability

Cisco IOS and IOS XE contain an out-of-bounds write vulnerability in the Group Encrypted Transport VPN (GET VPN) feature that could allow an authenticated, remote attacker who has administrative control of either a group member or a key server to execute malicious code or cause a device to crash.

CVE-2023-20109

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2023-10-10: attackers are using it right now.

CISA KEV: Listed; Added 2023-10-10 · federal fix-by 2023-10-31
EPSS (30 days): 2.5%; Higher than 85% of CVEs · 2026-11-01
CVSS v3.1: 6.6 Medium; CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

What CISA says

Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Vulnerability

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

NVD description · published 2023-09-27

A vulnerability in the Cisco Group Encrypted Transport VPN (GET VPN) feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker who has administrative control of either a group member or a key server to execute arbitrary code on an affected device or cause the device to crash. This vulnerability is due to insufficient validation of attributes in the Group Domain of Interpretation (GDOI) and G-IKEv2 protocols of the GET VPN feature. An attacker could exploit this vulnerability by either compromising an installed key server or modifying the configuration of a group member to point to a key server that is controlled by the attacker. A successful exploit could allow the attacker to execute arbitrary code and gain full control of the affected system or cause the affected system to reload, resulting in a denial of service (DoS) condition. For more information, see the Details ["#details"] section of this advisory.

Full record on NVD

Got a whole scan? Scan Hub runs this check on every finding in your Nessus, Qualys, Rapid7 or OpenVAS export and ranks the report by it.

Try it free

How to check if you are exposed to CVE-2023-20109

Find every Cisco IOS and IOS XE system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2023-20109.

US federal agencies had to fix this by 2023-10-31. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2023-20109. Check the vendor advisory for the exact fixed builds before you sign anything off.

Product	Vulnerable versions
Cisco IOS	12.4(22)md; 12.4(22)md1; 12.4(22)md2; 12.4(22)mda; 12.4(22)mda1; 12.4(22)mda2 and 668 more
Cisco IOS XE	3.3.0sg; 3.3.1sg; 3.3.2sg; 3.4.0sg; 3.4.1sg; 3.4.2sg and 358 more

Timeline

2023-09-27 · Published in the National Vulnerability Database
2023-10-10 · Added to CISA's Known Exploited Vulnerabilities catalog, 13 days after it was published
2023-10-31 · Fix-by date for US federal agencies, passed 1,097 days ago

Vendor advisories and fixes

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-getvpn-rce-g8qR68sx

Weakness type

CWE-787

More exploited Cisco vulnerabilities

CISA lists 102 exploited Cisco vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.