CVE-2023-20273: Cisco IOS XE Web UI Command Injection Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 23 Oct 2023, 1 day before the CVE record was published.
- How likely is exploitation in the next 30 days?
- 92.9%
EPSS score, percentile 99.8 of all scored records
- How severe?
- 7.2 High
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 27 Oct 2023: Verify that instances of Cisco IOS XE Web UI are in compliance with BOD 23-02 and apply mitigations per vendor instructions. For affected products (Cisco IOS XE Web UI exposed to the internet or to untrusted networks), follow vendor instructions to determine if a system may have been compromised and immediately report positive findings to CISA.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected: 16.1.1; 16.1.2; 16.1.3; 16.2.1; 16.2.2; 16.3.1; 16.3.2; 16.3.3; 16.3.1a; 16.3.4; 16.3.5; 16.3.5b
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
Verify that instances of Cisco IOS XE Web UI are in compliance with BOD 23-02 and apply mitigations per vendor instructions. For affected products (Cisco IOS XE Web UI exposed to the internet or to untrusted networks), follow vendor instructions to determine if a system may have been compromised and immediately report positive findings to CISA.
CISA due date for this action: 27 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-iosxe-webui-privesc-j22SaA4z
- https://nvd.nist.gov/vuln/detail/CVE-2023-20273
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 16.1.1 |
| Affected | 16.1.2 |
| Affected | 16.1.3 |
| Affected | 16.2.1 |
| Affected | 16.2.2 |
| Affected | 16.3.1 |
| Affected | 16.3.2 |
| Affected | 16.3.3 |
| Affected | 16.3.1a |
| Affected | 16.3.4 |
| Affected | 16.3.5 |
| Affected | 16.3.5b |
And 174 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 XE contains a command injection vulnerability in the web user interface. When chained with CVE-2023-20198, the attacker can leverage the new local user to elevate privilege to root and write the implant to the file system. Cisco identified CVE-2023-20273 as the vulnerability exploited to deploy the implant. CVE-2021-1435, previously associated with the exploitation events, is no longer believed to be related to this activity.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2023-20273 to its Known Exploited Vulnerabilities (KEV) catalog on 23 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 27 Oct 2023.
- The CVE record was published on 24 Oct 2023, 1 day after it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.2 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 92.9% (percentile 99.8), 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 web UI feature of Cisco IOS XE Software could allow an authenticated, remote attacker to inject commands with the privileges of root. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted input to the web UI. A successful exploit could allow the attacker to inject commands to the underlying operating system with root privileges.
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 |
|---|---|
| 23 Oct 2023 | Added to CISA KEV |
| 24 Oct 2023 | CVE record published |
| 27 Oct 2023 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
References
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