CVE-2026-20121

MEDIUM

A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defens...

Affects 0 products across 1 vendor.

CVSS 3.15.3
EPSS0.5%
Percentile39th
PatchUnknown
CVSS Vector — Plain English Remotely exploitable over the network, low complexity, no authentication required, no user interaction needed, impact contained to the vulnerable component, no confidentiality impact, no availability impact.
CWE Weakness Definitions
CWE-284: Improper Access Control

Software does not restrict or incorrectly restricts access to a resource.

Related Attack Patterns (CAPEC)
CAPEC-478 Modification of Windows Service Configuration
via CWE-284
CAPEC-479 Malicious Root Certificate
via CWE-284
CAPEC-546 Incomplete Data Deletion in a Multi-Tenant Environment
via CWE-284
CAPEC-550 Install New Service
via CWE-284
CAPEC-551 Modify Existing Service
via CWE-284
Show all 17

Mapping is CWE-to-CAPEC per MITRE CAPEC 3.9.

◆ AI Analysis — automated analysis, not human-reviewed

A medium severity vulnerability (CVE-2026-20121) affects the target system. A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remo...

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Frequently Asked Questions
What is CVE-2026-20121?
A medium severity vulnerability (CVE-2026-20121) affects the target system. A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remo...
What is the CVSS score for CVE-2026-20121?
CVE-2026-20121 has CVSS 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N. EPSS: 0.5%.
Is CVE-2026-20121 actively exploited?
No confirmed active exploitation of CVE-2026-20121 as of 2026-09-25.
How do I remediate CVE-2026-20121?
Apply vendor patches for CVE-2026-20121. Monitor Cisco advisories.
What systems are affected by CVE-2026-20121?
CVE-2026-20121 affects: Cisco.
Vulnerability Details
CVE IDCVE-2026-20121
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published2026-09-16
Last Modified2026-09-18
ICS Relevance80%
Weakness (CWE)
Improper Access Control
SourceNVD
Official Description

A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured access controls. This vulnerability is due to a logic error in populating group access control policies (ACPs) with OGS configured. An attacker could exploit this vulnerability by sending traffic that should be blocked through the device. A successful exploit could allow the attacker to bypass access controls and reach devices in protected networks.

Source: NIST NVD / MITRE CVE Database

Affected Products
VendorProductFixed Version
Cisco — —
Remediation

No patch URL on record. Monitor vendor security advisories directly.

Threat Intelligence
● Threat Intelligence Validated: September 2026 | Threat Age: 11 Days
CISA KEVNot in KEV catalog
Public ExploitNot confirmed
PoC CodeNot confirmed
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