CVE-2023-20198

Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE Software.

Critical Known exploited

Severity: 10.0 / 10; Critical · CVSS 3.1
Exploit chance (EPSS): 99.61%; Chance of exploitation in the next 30 days. Higher than 99.95% of scored vulnerabilities.
Known exploited: Yes; In CISA's catalog since Oct 16, 2023
Weakness: CWE-420 Unprotected Alternate Channel
Fix: None yet; No fixed version published

Exploited in the wild. Cisco IOS XE Web UI Privilege Escalation Vulnerability (Cisco IOS XE Web UI). Required action: 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. Due for U.S. federal agencies by Oct 20, 2023.

Description

Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE Software. We are updating the list of fixed releases and adding the Software Checker. Our investigation has determined that the actors exploited two previously unknown issues. The attacker first exploited CVE-2023-20198 to gain initial access and issued a privilege 15 command to create a local user and password combination. This allowed the user to log in with normal user access. The attacker then exploited another component of the web UI feature, leveraging the new local user to elevate privilege to root and write the implant to the file system. Cisco has assigned CVE-2023-20273 to this issue. CVE-2023-20198 has been assigned a CVSS Score of 10.0. CVE-2023-20273 has been assigned a CVSS Score of 7.2. Both of these CVEs are being tracked by CSCwh87343.

How to fix

No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.

Severity breakdown

CVSS 3.1 10.0

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: High

Weakness

CWE-420: Unprotected Alternate Channel

The product protects a primary channel, but it does not use the same level of protection for an alternate channel.

How to prevent it

Architecture and Design: Identify all alternate channels and use the same protection mechanisms that are used for the primary channels.

References

Advisories

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webui-p…

Timeline

Oct 16, 2023 Added to CISA's Known Exploited Vulnerabilities catalog
Oct 16, 2023 Published
Oct 20, 2023 Remediation due for U.S. federal agencies
Jun 17, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-wxxx-gvqv-xp7p LiteLLM has a sandbox escape in custom-code guardrail	High	Same weakness, CWE-420
CVE-2025-54309 CrushFTP 10 before 10.8.5 and 11 before 11.3.4_23, when the DMZ proxy feature is not used, mishandles AS2 validation and consequently allows remote attackers…	Critical Known exploited	Same weakness, CWE-420
GHSA-xwgj-vpm9-q2rq Vulnerable juju introspection abstract UNIX domain socket	Medium	Same weakness, CWE-420
GHSA-232p-vwff-86mp Docker Swarm encrypted overlay network may be unauthenticated	High	Same weakness, CWE-420
GHSA-6wrf-mxfj-pf5p Docker Swarm encrypted overlay network with a single endpoint is unauthenticated	Medium	Same weakness, CWE-420
GHSA-wqv3-8cm6-h6wg Improper Authentication in Kubernetes	High	Same weakness, CWE-420

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