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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 31 Oct 2023.
iOSOperating system · Cisco

CVE-2023-20109

MEDIUM · 6.6 CVSS v3.1 Published 2023-09-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

GET VPN feature in Cisco IOS/IOS XE has insufficient validation of attributes in the GDOI and G-IKEv2 protocols. An authenticated attacker with administrative control of a key server or group member can send specially crafted GDOI/G-IKEv2 messages to execute arbitrary code or cause device reload.

MitigationApply Cisco IOS/IOS XE patches when available. Restrict administrative access to key servers, verify key server authenticity, and monitor for unauthorized configuration changes on group members.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
iOSOperating system
Affected:= 12.4\(22\)md= 12.4\(22\)md1= 12.4\(22\)md2= 12.4\(22\)mda= 12.4\(22\)mda1= 12.4\(22\)mda2= 12.4\(22\)mda3= 12.4\(22\)mda4= 12.4\(22\)mda5= 12.4\(22\)mda6= 12.4\(22\)t= 12.4\(22\)t1
Ios XeOperating system
Affected:= 3.3.0sg= 3.3.1sg= 3.3.2sg= 3.4.0sg= 3.4.1sg= 3.4.2sg= 3.4.3sg= 3.4.4sg= 3.4.5sg= 3.4.6sg= 3.4.7sg= 3.4.8sg

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm GET VPN is enabled
    Run 'show crypto gdoi' or check running configuration for 'crypto gdoi' commands to see if Group Encrypted Transport VPN is configured
    Affected if GET VPN feature is configured and active on the device
  2. Identify installed iOS or IOS XE version
    Run 'show version' and locate the IOS/IOS XE version string in the output
    Affected if The version matches any of these: Cisco iOS 12.4(22)md/t variants (12.4(22)md, 12.4(22)md1, 12.4(22)md2, 12.4(22)mda, 12.4(22)mda1, 12.4(22)mda2, 12.4(22)mda3, 12.4(22)mda4, 12.4(22)mda5, 12.4(22)mda6, 12.4(22)t, 12.4(22)t1) or Cisco IOS XE 3.3.0sg through 3.4.8sg variants (3.3.0sg, 3.3.1sg, 3.3.2sg
  3. Verify key server configuration
    Run 'show crypto gdoi ks' to display key server details, or run 'show running-config | include crypto gdoi' to review key server IP addresses and group definitions
    Affected if The device is configured to use a key server that is not trusted or is externally accessible/unverified
  4. Check group member configuration
    Run 'show crypto gdoi gm' to display group member registration status and identify the key server IP they are using
    Affected if Any group member is registered to an unauthorized or attacker-controlled key server

The environment is affected if GET VPN is configured on a Cisco iOS or IOS XE device running an affected version (12.4(22)md/t variants or 3.3.xsg through 3.4.xsg) and the device uses an untrusted or compromised key server.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco IOS/IOS XE patches when available. Restrict administrative access to key servers, verify key server authenticity, and monitor for unauthorized configuration changes on group members.

Fix this in iOS Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-20109 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data