Known exploited · Cisco
CVE-2023-20109: Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Vulnerability
What it is
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.
- Vendor
- Cisco
- Product
- IOS and IOS XE
- Added to KEV
- October 10, 2023
- CISA due date
- October 31, 2023
- Ransomware use
- Unknown
- Weakness
- CWE-787: Out-of-bounds Write
What CISA requires
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Forensic triage
No
What to do now
- Find every instance of IOS and IOS XE you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before October 31, 2023 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
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Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.