VulnerabilityPublished 14 Aug 2025

CVE-2025-20219: Cisco Adaptive Security Appliance (ASA) Software · Improper Access Control

Affects Cisco Adaptive Security Appliance (ASA) SoftwareSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 14 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Cisco Cisco Adaptive Security Appliance (ASA) Software	Affected 9.18.2 – 9.22.1.2 44 affected builds	Fixed in–

AI-suggested

Immediate Actions: Monitor Cisco’s official security advisories and update notifications for patches addressing CVE-2025-20219. Apply patches promptly once available.
Network Segmentation: Restrict access to loopback interfaces by implementing strict network segmentation and limiting which devices or management stations can communicate with these interfaces.
Access Control Review: Conduct a thorough review of firewall access control policies, especially those involving loopback interfaces, to identify and minimize exposure.
Intrusion Detection: Deploy network intrusion detection/prevention systems (IDS/IPS) to monitor for anomalous traffic patterns targeting loopback interfaces or unusual access attempts.
Configuration Hardening: Disable unnecessary services or interfaces on ASA devices, and ensure that loopback interfaces are configured with the least privilege necessary.
Logging and Monitoring: Enable detailed logging on ASA devices to detect any attempts to send unauthorized traffic to loopback interfaces and establish alerting mechanisms for suspicious activity.
Incident Response Preparedness: Prepare incident response plans to quickly investigate and remediate any suspected exploitation attempts.
Vendor Engagement: Engage with Cisco support to obtain guidance and early access to patches or workarounds if available.
Alternative Controls: Where patching is delayed, consider deploying compensating controls such as upstream filtering or additional firewall layers to block unauthorized traffic targeting loopback interfaces.

Description

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.

Impact

For European organizations, this vulnerability poses a significant risk to network security posture, especially for enterprises and service providers relying on Cisco ASA and FTD devices for perimeter defense and internal segmentation. The ability to bypass access control rules on loopback interfaces could allow attackers to circumvent firewall policies designed to isolate sensitive management or routing traffic. This could lead to unauthorized access to internal network segments, exposure of critical infrastructure components, or facilitation of further attacks such as lateral movement or privilege escalation within the network. Organizations in sectors with stringent regulatory requirements (e.g., finance, healthcare, critical infrastructure) may face compliance risks if this vulnerability is exploited to access protected data or systems. Additionally, the lack of authentication requirement and remote exploitability increases the attack surface, making it easier for external threat actors to attempt exploitation. Although no known exploits exist currently, the widespread deployment of Cisco ASA devices in Europe means that successful exploitation could have broad impact. The vulnerability could also undermine trust in network security controls, potentially leading to operational disruptions or data breaches if attackers leverage this bypass to stage more complex attacks.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-acl-bypass-mtPze9Yh (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Aug 2025, 17:23 UTC

Technical details

References

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