CVE-2023-20109: Cisco IOS and IOS XE Group Encrypted Transport VPN Out-of-Bounds Write Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 10 Oct 2023, 13 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 2.5%
EPSS score, percentile 84.5 of all scored records
- How severe?
- 6.6 Medium
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline 31 Oct 2023. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 12.4(24)T
- 12.4(24)T3
- 12.4(22)T1
- 12.4(24)T5
- 12.4(24)T4
- 12.4(22)T
and 18 more in the table below
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: 31 October 2023.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-getvpn-rce-g8qR68sx
- https://nvd.nist.gov/vuln/detail/CVE-2023-20109
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 12.4(24)T |
| Affected | 12.4(24)T3 |
| Affected | 12.4(22)T1 |
| Affected | 12.4(24)T5 |
| Affected | 12.4(24)T4 |
| Affected | 12.4(22)T |
| Affected | 12.4(24)T8 |
| Affected | 12.4(24)T2 |
| Affected | 12.4(22)T5 |
| Affected | 12.4(22)T4 |
| Affected | 12.4(24)T1 |
| Affected | 12.4(24)T7 |
And 662 more version entries in the CVE record.
| Status | Versions |
|---|---|
| Affected | 3.7.0S |
| Affected | 3.7.1S |
| Affected | 3.7.2S |
| Affected | 3.7.3S |
| Affected | 3.7.4S |
| Affected | 3.7.5S |
| Affected | 3.7.6S |
| Affected | 3.7.7S |
| Affected | 3.7.4aS |
| Affected | 3.7.2tS |
| Affected | 3.7.0bS |
| Affected | 3.7.1aS |
And 352 more version entries in the CVE record.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this 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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2023-20109 to its Known Exploited Vulnerabilities (KEV) catalog on 10 Oct 2023.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 31 Oct 2023.
- The CVE record was published on 27 Sep 2023, 13 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 6.6 (Medium), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 2.5% (percentile 84.5), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 27 Sep 2023 | CVE record published |
| 10 Oct 2023 | Added to CISA KEV |
| 31 Oct 2023 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
References
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