CVE-2026-20121: Improper Access Control
Source GCVE Database
Public exploit available · CVSS 5.3 Medium · patch available : patch Cisco Secure Firewall Adaptive Security Appliance (ASA) Software as a priority.
Data as of 31 Oct 2026, 20:20 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:CExploitation evidence
Disclosed: evidence found.
CVE published 16 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software | Affected
| Fixed in– |
| CiscoCisco Secure Firewall Threat Defense (FTD) Software | Affected
| Fixed in– |
Description
A logic error in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall ASA and FTD software allows unauthenticated remote attackers to bypass configured access controls. This vulnerability enables attackers to send traffic that should be blocked through the device, potentially reaching protected network devices. The issue affects the way group access control policies are populated when OGS is configured.