VulnerabilityPublished 4 Mar 2026

CVE-2026-20015: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Memory Leak

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

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Not known to be exploited · CVSS 5.8 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

5.8Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 25% 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:C/C:N/I:N/A:L

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

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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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
CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software	Affected 9.18.1 – 9.23.1 57 affected builds	Fixed in–
CiscoCisco Secure Firewall Threat Defense (FTD) Software	Affected 7.2.0 – 7.7.0 34 affected builds	Fixed in–

AI-suggested

Apply Cisco's security patches and updates for ASA and FTD software as soon as they become available, ensuring all affected versions are upgraded to fixed releases.
Implement network-level filtering to restrict incoming IKEv2 traffic to trusted IP addresses and VPN peers only, minimizing exposure to unauthenticated attackers.
Monitor firewall logs and network traffic for unusual or malformed IKEv2 packets that could indicate exploitation attempts.
Employ rate limiting or traffic shaping on IKEv2 ports (typically UDP 500 and 4500) to reduce the risk of resource exhaustion from crafted packets.
Regularly audit firewall configurations and firmware versions to ensure compliance with security best practices.
Prepare incident response plans that include procedures for rapid device reload and recovery to minimize downtime in case of exploitation.
Consider deploying redundant firewall appliances or high-availability configurations to maintain service continuity during an attack or device reboot.

Description

A vulnerability in the IKEv2 feature of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device that may impact the availability of services to devices elsewhere in the network. This vulnerability is due to a memory leak when parsing IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to exhaust resources, causing a DoS condition that will eventually require the device to be manually reloaded.

Impact

The primary impact of CVE-2026-20015 is a denial-of-service condition that can disrupt network security infrastructure by incapacitating Cisco ASA and FTD devices. This disruption can lead to loss of firewall protection, VPN connectivity, and traffic filtering, potentially exposing internal networks to further attacks or causing business interruptions. Organizations relying on these devices for critical network security functions may experience degraded service availability, impacting end-users and dependent systems. The vulnerability does not allow data theft or modification but can indirectly facilitate other attacks by disabling security controls. The requirement for manual reload after exploitation increases operational overhead and downtime. Given the widespread use of Cisco ASA and FTD in enterprise, government, and service provider environments globally, the impact can be significant, especially in sectors where continuous network availability is critical, such as finance, healthcare, telecommunications, and government agencies.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2-dos-eBueGdEG (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 20:06 UTC

Technical details

References

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