dbcve.org
Improper Access ControlWeakness · CWE-284

CVE-2025-20219

MEDIUM · 5.3 CVSS v3.1 Published 2025-08-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the implementation of access control rules for loopback interfaces in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to send traffic that should have been blocked to a loopback interface. This vulnerability is due to improper enforcement of access control rules for loopback interfaces. An attacker could exploit this vulnerability by sending traffic to a loopback interface on an affected device. A successful exploit could allow the attacker to bypass configured access control rules and send traffic that should have been blocked to a loopback interface on the device.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in Cisco Secure Firewall ASA and FTD software allows unauthenticated remote attackers to bypass access control rules on loopback interfaces. Traffic that should be blocked can reach loopback interfaces due to improper enforcement of access control rules for these interfaces.

MitigationApply the Cisco software update that fixes this vulnerability. Review and verify that access control policies are properly enforced on all loopback interfaces after patching.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Cisco firewall product
    Run 'show version' or check the system banner to confirm whether the device runs ASA (Adaptive Security Appliance) or FTD (Firepower Threat Defense) software
    Affected if The device runs ASA or FTD software from any version
  2. Determine the software version
    Execute 'show version' and locate the software release number (e.g., 9.x for ASA or 7.x for FTD). Compare this version against the affected version ranges provided in Cisco's advisory for CVE-2025-20219
    Affected if The installed version falls within the vulnerable version range
  3. Verify loopback interface configuration
    Execute 'show interface loopback' or 'show running-config interface Loopback' to list any configured loopback interfaces on the device
    Affected if One or more loopback interfaces are configured on the device
  4. Review access control rules applied to loopback interfaces
    Use 'show access-list' or the management console to examine access control policies. Identify rules that reference loopback interfaces or the 'any' keyword that could apply to loopback traffic
    Affected if Access control rules exist that should filter traffic to loopback interfaces but may not be enforced due to the vulnerability
  5. Confirm access control enforcement on loopback interfaces
    Review the access control policy assignment via 'show access-group' or the Firepower Management Center for FTD. Verify that loopback interfaces are explicitly included in the inspection policy
    Affected if Loopback interfaces are not explicitly included in access control policy enforcement, or the policy shows 'perimetric' or incomplete interface coverage

The environment is affected if the device runs a vulnerable version of Cisco ASA or FTD software AND has loopback interfaces configured with access control rules that are not properly enforced on those interfaces.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco software update that fixes this vulnerability. Review and verify that access control policies are properly enforced on all loopback interfaces after patching.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing6.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,780
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,448.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-20219 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20219 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data